随着全球新一轮科技革命和产业变革新机遇的到来，数字经济正成为重组全球要素资源、重塑全球经济结构、改变全球竞争格局的关键力量。数字经济如何影响出口贸易是当下社会各界关注的重要问题。回顾过往，中国对外贸易快速发展，货物贸易规模稳居世界第一，对外贸易结构也持续优化。立足当下，中国坚持高水平对外开放，加快构建以国内大循环为主体、国内国际双循环相互促进的新发展格局。但与此同时，当今世界百年未有之大变局加速演进，经济全球化逆流涌动，对外贸易环境发生深刻而复杂的变化。中国牢牢把握数字经济的发展机遇，使数字经济成为推动高水平对外开放的新引擎。在此背景下，研究数字经济发展对中国出口增长产生何种影响具有重要的理论与现实意义。本文将从地区层面的数字经济发展和企业层面的数字化转型与数字技术应用三个维度，采用理论分析与实证研究相结合的方法检验数字经济发展对中国出口增长的影响。

本文首先从理论层面分析了地区数字经济发展以及企业数字化转型和数字技术应用如何通过降低与出口目的国的信息摩擦、稳定供应链关系、重塑技术范式和优化就业技能结构等途径影响中国出口增长与出口升级，然后利用2007-2016年中国海关数据库、上市企业财务数据、供应链数据、上市企业数字化转型数据、全国企业税收调查数据、中国城市统计年鉴、2014-2019年中关村国家自主创新示范区企业数据等多个数据库，分别从地区层面和企业层面实证分析了数字经济发展对地区出口增长、企业出口增长与出口升级的作用大小和影响机制。

本文由七章构成。第一章为导论。第二章为文献综述，梳理了与数字经济和出口贸易相关的研究成果，并对以往文献进行分析与述评。第三章为中国数字经济发展与出口贸易的特征事实，借助国家统计局、中国信息通信研究院、联合国统计属等多种来源数据资料对中国的数字经济发展与出口贸易增长进行了描述统计，主要包括对中国数字经济规模以及地区与行业发展现状的刻画、对中国企业数字化发展趋势的分析、对中国出口贸易特征事实的描述。第四章从地区层面考察了数字经济发展对中国城市出口增长的影响，首先，从信息摩擦的视角对于数字经济发展影响出口贸易的作用渠道进行了理论分析；其次，基于2011-2016年中国海关数据库、中国城市统计年鉴实证检验了数字经济发展水平对于城市出口增长的影响，并重点从降低市场搜寻成本与信息沟通成本、促进研发投入与创新产出等渠道进行机制检验；最后，基于合成控制法对云计算创新服务试点政策的出口促进效应进行拓展分析。第五章从企业层面考察了数字化转型、供应链关系与企业出口表现，首先，本章通过理论分析提出数字化转型能够降低与上游企业信息不对称，通过提高供应链关系的稳定性和获取更优质供应商来促进企业出口规模扩张；其次，借助丰富的2007-2016年上市企业财务数据、供应链数据、上市企业数字化转型数据、全国企业税收调查数据以及中国海关数据库的匹配数据，通过双向固定效应模型、工具变量法、三重差分模型等实证研究方法对数字化转型影响企业出口表现的影响大小和作用机制进行了充分验证；最后，本章也基于边际分解的视角对数字化转型促进企业出口增长的边际效应展开讨论。第六章从企业层面考察了数字技术应用对企业出口增长与出口升级的影响，本章重点采用独特的2014-2019年中关村国家自主创新示范区企业数据集，借助工具变量法、前定变量分析、双重差分模型等实证研究策略，以企业实际采用数字技术的情况构建数字技术应用强度指标，在理论分析基础上实证检验了数字技术应用对企业出口增长以及出口升级的影响大小和作用机制；同时，本章通过对数字技术、企业类型和企业规模分类得到了一系列异质性结果，并较为创新性地对企业研发费用加计扣除政策在上述关系中起到的调节作用展开讨论，为深入了解数字技术产生的作用有较大帮助。第七章为结论与政策建议，本章总结了主要研究结论，并提出如何进一步推动数字经济发展、如何通过数字经济和数字技术助力高水平对外开放的相关建议。本文的主要研究结论如下：

（1）中国数字经济发展与出口贸易的特征事实。首先，从中国数字经济发展的特征来看，2005年以来中国数字经济规模持续增长，占国内生产总值的比重也逐渐提升。但数字经济发展存在地区间不平衡问题，尤其以东部沿海地区发展水平最高。不同行业的数字经济发展水平也有所不同，第三产业始终处于领先地位，第二产业稳步提升，第一产业初见成效。其次，从企业数字化的特征来看，自2006年开始中国企业的数字化水平稳步提高，数字经济发展卓有成效，但企业数字化水平也存在行业与地区异质性。最后，从中国出口贸易的特征来看，1980年以来中国出口规模持续增长，出口总额占GDP的比重呈先上升后下降的趋势，中国在全球的贸易地位也不断上升，自2009年以来稳居全球第一大出口贸易国。与此同时，中国的出口贸易结构不断优化，在贸易方式上由加工贸易与一般贸易并重逐渐转化为一般贸易为主，在出口产品结构上工业制成品的出口占比进一步提升。

（2）从信息摩擦视角考察数字经济发展影响城市出口增长的研究结论。第一，数字经济发展显著促进了城市出口贸易增长，且进一步按照城市—产品—目的国三个维度对城市出口贸易进行分解后发现数字经济发展促进了城市—产品层面出口规模增长以及城市—产品—目的国数量的提高。在通过外生政策冲击、工具变量法解决内生性问题，以及进行一系列稳健性检验后，该研究结论保持稳健。第二，数字经济发展促进了城市出口贸易从加工贸易模式向一般贸易模式的转型升级，数字经济发展对于出口贸易的促进作用在欠发达目的地表现的更为突出。第三，基于信息摩擦视角的影响渠道表明，数字经济发展一方面降低了市场搜寻成本，使中国出口至距离更远的国家或地区，另一方面也降低了信息沟通成本，提高了对文化距离更远的国家或地区的出口贸易额。此外，数字经济发展通过激励研发创新也有利于出口贸易增长。第四，基于云计算创新服务试点政策采用合成控制法研究策略的拓展分析发现，数字经济发展相关政策也能够有效促进城市出口贸易增长。

（3）从供应链视角考察数字化转型影响企业出口表现的研究结论。第一，企业数字化转型显著促进了企业出口规模扩张。这一结论在将全部解释变量滞后一期、采用工具变量法以及将“两化融合”试点政策作为外生冲击解决内生性问题后依然成立。第二，技术应用层面的数字化转型显著促进了企业出口规模增长，而底层技术层面的数字化转型影响效果不明显。另外，民营企业相对国有企业、沿海地区企业相对内陆地区企业，数字化转型的出口促进效果更显著。第三，机制检验结果表明，数字化转型一方面降低了与上游企业的信息不对称，提高供应链关系稳定性，另一方面使企业与更优质的供应商建立联系，提高上游投入品规模与质量，最终促进出口规模扩张。第四，基于边际效应的拓展分析发现，数字化转型对于出口贸易的促进作用主要体现为既有出口产品种类出口额的提升，而没有体现在探索和扩展新的出口产品种类上。

（4）从技术范式视角考察数字技术应用影响企业出口增长与出口升级的研究结论。第一，数字技术应用显著促进了企业出口增长与出口升级，该结论通过了事前平行趋势检验并具有长期动态效应，在排除了减税政策、中美贸易摩擦等同期政策的干扰，并考虑数字技术应用强度、采用倾向得分匹配法筛选控制组、进行安慰剂检验后研究结论保持稳健。第二，底层技术层面的数字技术主要对企业高新技术产品出口产生了显著影响，即产生出口升级效应，而技术应用层面的数字技术带来了显著的出口增长效应，促进了出口概率和出口总额的提高。此外，数字技术应用的出口增长与出口升级效应主要体现在民营企业以及大中型企业中。第三，机制检验发现，数字技术应用不仅促进了企业研发投入和创新产出，通过技术范式重塑影响出口表现，而且使得企业对研发人员和高技能劳动力的需求增加，通过优化企业内部就业技能结构进一步产生出口增长与升级效应。第四，国家创新导向减税政策能够放大数字技术对出口贸易的促进作用。

（5）基于前述研究结论，本文在以下几方面具有政策参考价值：第一，加快发展数字经济和数字技术，重点攻克数字经济领域关键技术，储备数字化相关人才。第二，促进数字技术与贸易发展相融合，鼓励贸易企业加快数字化转型，着力打造贸易新业态新模式。第三，发挥数字经济领先城市的带头作用，打破数字经济区域发展不平衡，以企业间技术合作、异地设立研发机构等方式促进全国范围内技术知识扩散。第四，积极利用数字技术提高对供应链管理能力，通过建立供应商信息库及时甄别和筛选存在财务风险的上游供应商企业，保障供应链稳定。第五，发挥国家经济政策与数字经济发展的协同作用，从政府角度适度扩大减税政策惠及范围，从企业角度借助国家政策提供的便利条件主动进行数字技术研发和数字化转型。

With the arrival of a new round of global technological revolution and new opportunities for industrial transformation, digital economy is becoming a key force to restructure global factor resources, reshape global economic structure and change global competition pattern. How digital economy affects export trade is an important issue concerned by people. Looking back, China's foreign trade has been booming, with its trade in goods ranking first in the world and its trade structure constantly improving. At the same time, profound changes unseen in a century are accelerating, de-globalization is surging, and the foreign trade environment is undergoing profound and complex changes. China firmly grasps the new opportunities in the development of global digital economy, adheres to digital empowerment, promotes the deep integration of digital technology and trade development, and makes the digital economy a new engine for high-level opening-up. In this context, it is of great theoretical and practical significance to study the impact of digital economy development on China's export growth. This dissertation will examine the impact of digital economy development on China's export growth from three dimensions by combining theoretical analysis and empirical research, including digital economy development at the regional level, as well as the digital transformation and digital technology application at the enterprise level.

This dissertation theoretically analyzes how regional digital economy development, as well as enterprise digital transformation and digital technology application affect China's export growth and export upgrading by reducing information friction with export destination countries, stabilizing supply chain relations, reshaping technological paradigm and optimizing employment skill structure. Then, using several databases such as China Customs database from 2007 to 2016, financial data of listed enterprises, supply chain data, digital transformation data of listed enterprises, National Enterprise Tax survey data, China City Statistical Yearbook, and enterprise data of Zhongguancun Science Park from 2014 to 2019, this dissertation empirically analyzes the effect of the development of digital economy on export growth and export upgrading from the regional level and enterprise level respectively.

This dissertation consists of seven chapters. Chapter 1 and Chapter 2 are introduction and literature review. Chapter 3 is about the characteristics and stylized facts of China's digital economy development and export trade. It mainly includes the description of the scale of China's digital economy and the development status of different regions and industries, the analysis of the digital transformation trend of Chinese enterprises, the description of the characteristics and stylized facts of China's export trade. Chapter 4 examines the impact of digital economy development on city export from the regional level. Firstly, from the perspective of information friction, we makes a theoretical analysis of the channels of digital economy development on export trade. Secondly, based on the 2011-2016 China Customs database and China City Statistical Yearbook, this chapter empirically tests the impact of digital economy development on city export growth, and focuses on the mechanism test from the channels of reducing market search cost and information communication cost, as well as promoting R&D investment and innovation output. Finally, based on the synthetic control method, this chapter extends the analysis on the export promotion effect of the cloud computing innovation service pilot policy. Chapter 5 examines digital transformation, supply chain relationship and export performance from the enterprise level. Firstly, through theoretical analysis, this chapter proposes that digital transformation can reduce the information asymmetry with upstream enterprises, and promote the expansion of enterprise export by improving the stability of supply chain relationship and obtaining better suppliers. Secondly, with the use of rich financial data of listed enterprises from 2007 to 2016, as well as supply chain data, digital transformation data of listed enterprises, National Enterprise Tax survey data and China Customs database, we have verified the impact and mechanism of digital transformation on export performance of enterprises through the two-way fixed effect model, instrumental variable method, DDD model and other empirical research methods. Finally, this chapter also discusses the marginal effect of digital transformation on enterprises export growth from the perspective of marginal decomposition. Chapter 6 examines the impact of digital technology application on export growth and export upgrading from the enterprise level. This chapter focuses on the unique enterprise data set of Zhongguancun Science Park from 2014 to 2019, and adopts empirical research strategies such as instrumental variable method, predetermined variables analysis and DID model. The index of digital technology application intensity is constructed based on the actual application of digital technology in enterprises. Based on theoretical analysis, the influence and mechanism of digital technology application on export growth and export upgrading are tested empirically. At the same time, this chapter has obtained a series of heterogeneous results through the classification of digital technology, enterprise type and enterprise size, and innovatively discussed the moderating effect of enterprise R&D expense additional deduction policy on the above relationship, which is of great help to further understand the role of digital technology. Chapter 7 is the conclusion and policy enlightenment. This chapter mainly summarizes the main conclusions of the full paper, and puts forward relevant policy recommendations on how to further promote the development of digital economy and how to promote the high-level opening up through digital economy and digital technology. Here are the main conclusions:

(1) The stylized facts of China's digital economy and export. First, the scale of China's digital economy has continued to expand since 2005, and its proportion in GDP has also gradually increased. However, the development of digital economy has the problem of inter-regional imbalance, especially the eastern coastal areas have the highest level of development. There are also differences in the development level of digital economy in different industries, among which the tertiary industry has always been in a leading position, the secondary industry has been steadily improving, and the primary industry has achieved initial results. Second, the level of digitalization of Chinese enterprises has been steadily improved since 2006, but the digitalization level of enterprises also exists industry and regional heterogeneity. Third, the scale of China's export has been growing continuously since 1980, and the proportion of total export in GDP has been rising first and then declining. China's status in global trade has also been rising, and it has been the world's largest export country since 2009. At the same time, China's export trade structure has been constantly optimized, the trade mode has gradually changed from processing trade to ordinary trade, and the export proportion of manufactured industrial products has further increased.

(2) Research findings of digital economy development affecting urban export growth from the perspective of information friction. Firstly, digital economy development significantly promotes the growth of urban export trade. Further decomposition of urban export trade along the dimensions of city-product-destination reveals that digital economy development promotes the growth of export scale at the city-product level, as well as an increase in the number of city-product-destination combinations. The research findings remain robust after addressing endogeneity issues through exogenous policy shocks, instrumental variable methods, and a series of robustness checks. Secondly, the development of digital economy promotes the transformation and upgrading of urban export trade from processing trade mode to ordinary trade mode. The promotion effect of digital economy development on export trade is more pronounced in underdeveloped destination countries. Thirdly, from the perspective of information friction, the impact channel indicates that on one hand, the development of digital economy reduces market search costs, enabling China to export to countries that are further away, on the other hand, it also reduces information communication costs and increases the export trade volume to countries with greater cultural distance. Furthermore, the development of digital economy simultaneously promotes R&D investment and innovation output, thereby facilitating export trade growth. Finally, based on the expansion analysis of the synthetic control method strategy regarding the cloud computing innovation service pilot policy, it is found that digital economy development policies can also effectively promote urban export trade growth.

(3) Research findings of digital transformation affecting enterprise export performance from the perspective of supply chain. Firstly, the digital transformation of enterprises has significantly promoted the expansion of export scale. This conclusion is still valid after all the explanatory variables are lagged by one period, the instrumental variable method is adopted, and the pilot policy of integration of information and industrialization is taken as an exogenous shock to solve the endogenous problem. The conclusion also remains robust after excluding contemporaneous policies. Secondly, the results of heterogeneity analysis show that the digital transformation at the technology application level has significantly promoted the growth of enterprises' export scale, while the effect of the digital transformation at the underlying technology level is not obvious. In addition, the export promotion effect of digital transformation is more significant for private enterprises than for state-owned enterprises, and for enterprises in coastal areas than for enterprises in inland areas. Thirdly, the results of the mechanism test show that digital transformation, on the one hand, reduces the information asymmetry with upstream enterprises and improves the stability of supply chain relations, on the other hand, enables enterprises establish contact with better suppliers, improve the scale and quality of upstream inputs, and ultimately promote the expansion of export trade. Fourthly, the analysis based on the marginal effect finds that the promotion effect of digital transformation on export trade is mainly reflected in the increase of the export value of existing product categories, but not in the exploration of new export product categories.

(4) Research findings of digital technology application affecting the export growth and export upgrading of enterprises from the perspective of technology paradigm. Firstly, the application of digital technology has significantly promoted the export growth and export upgrading of enterprises. This conclusion passed the parallel pretrend test and had a long-term dynamic effect. After excluding the concurrent policies such as tax reduction policy and China-Us trade friction, as well as considering the application intensity of digital technology, using the propensity score matching method to select the control group, the conclusion remains robust. Secondly, the digital technology at the underlying technology level mainly has a significant impact on the export of high-tech products of enterprises, that is, the export upgrading effect, while the digital technology at the technology application level has a significant export growth effect, promoting the increase of export probability and export scale. In addition, the export growth and export upgrading effects of digital technology application are mainly shown in private enterprises as well as large and medium-sized enterprises. Thirdly, the mechanism test finds that the application of digital technology not only promotes the R&D investment and innovation output of enterprises, therefore affects the export performance through the reshaping of technological paradigm, but also increases the demand for R&D personnel and highly skilled labor, which further generates export growth and upgrading effect by optimizing the internal employment skill structure of enterprises. Fourthly, the national innovation-oriented tax reduction policy can amplify the promotion effect of digital technology on export trade.

(5) Based on the above research conclusions, this dissertation has policy enlightenments in the following aspects: First, accelerate the development of digital economy and digital technology, focus on tackling key technologies in the field of digital economy, and reserve digital-related talents. Second, we should promote the deep integration of digital technology and trade development, encourage trade enterprises to accelerate digital transformation, and strive to create new forms of trade. Third, give full play to the leading role of leading cities in the digital economy, break the unbalanced regional development of the digital economy, and promote the diffusion of technological knowledge nationwide by means of technological cooperation among enterprises and the establishment of R&D institutions in different places. Fourth, actively use digital technology to improve supply chain management ability, through the establishment of supplier information database timely screening of upstream supplier enterprises with financial risks, to ensure the stability of supply chain. Fifth, we should give full play to the synergistic effect of national economic policies and the development of digital economy, moderately expand the benefit scope of tax reduction policies from the perspective of the government, and take the initiative to carry out digital technology research and digital transformation from the perspective of enterprises by making good use of the convenient conditions provided by policies.