随着经济全球化发展，国际贸易中关税水平不断降低，各国转而设置各类非关税贸易壁垒，成为阻碍国际贸易发展的主要障碍。随着中国在全球价值链中地位的不断提升，美国等老牌经济体逐渐感受到中国对其经济主导地位的威胁，对我国设置了各类非关税贸易壁垒，对我国国际贸易发展造成冲击。学界现有研究主要从理论角度进行归因分析，或从微观层面针对涉及某具体行业的非关税贸易壁垒进行实证研究。因此，从宏观层面针对美国对华施加非关税贸易壁垒的成因开展实证研究具有重要的理论、实践意义，有助于为我国应对各类非关税壁垒提供理论基础，促进中国进出口贸易健康发展。

在此背景下，本研究针对美国对华实施非关税贸易壁垒的成因开展理论分析与实证研究，采用2008—2021年美国对我国施加非关税贸易壁垒数据、中美分产业各类宏观经济数据与中美国际贸易关税数据，对学界现有结论进行理论分析，并从产品竞争、宏观经济、关税水平、政治博弈等角度选取核心解释变量，建立负二项回归模型，实证检验其对美国对华新施加非关税贸易壁垒数量的影响。并通过滞后解释变量、更换被解释变量、更换回归模型等方式进行稳健性检验。最后从不同类型、不同严重程度的非关税贸易壁垒等角度对模型进行异质性分析。

主要研究结果包括：（1）当中国出口产品技术复杂度提升，美国对华关税水平提升，中国对美国实施非关税贸易壁垒数量提升，以及美国内部宏观经济环境恶化时，美国会对我国设置更多的非关税贸易壁垒。（2）美国对华“非市场经济”的量裁是中美政治经济博弈下的行政规定，中国市场化程度的提升并不能有效减少美国对华施加非关税贸易壁垒的数量。（3）美国对华非关税贸易壁垒的设置有着较强的行业异质性，美国对其制造业、信息技术服务业的保护程度高于农林牧渔业等基础产业；面对中国出口技术复杂度与中对美非关税贸易壁垒数量的提升，美国倾向设置更多的出口激励类非关税贸易壁垒，以帮助国内企业在国际贸易中占据有利地位；面对国内宏观经济环境的恶化，美国更倾向设置更多的本地补贴、进口限制类非关税贸易壁垒，拉动内部经济增长；整体而言，各解释变量对较严重的非关税贸易壁垒数量影响较大，对轻度的非关税贸易壁垒数量影响较小。

With the development of economic globalization, the number of tariff trade barriers in international trade has decreased, and countries around the world have turned to setting various non-tariff trade barriers, which become the main obstacle to the development of international trade. In recent years, with the rapid development of China's economy and the continuous improvement of its position in the global value chain, established economies such as the United States have gradually felt the threat of China to their economic dominance, and have set various non-tariff trade barriers to China, which has had an impact on the development of international trade in China. The existing researches mainly focus on attribution analysis from a theoretical perspective, or empirical research on non-tariff trade barriers involving a specific industry or product at the micro level. Therefore, conducting empirical research on the causes of non-tariff trade barriers imposed by the United States on China from a macro perspective has important theoretical and practical significance, which can provide a theoretical basis for China to respond to various types of non-tariff barriers and promote the healthy development of China's import and export trade.

Under this background, using the data of non-tariff trade barriers imposed by the United States on China from 2008 to 2021, various macroeconomic and tariff data of China-US international trade, this study analyzes the existing conclusions from the perspective of product competition, macro-economy, tariff level, selects core explanatory variables and establishes a negative binomial regression model to empirically test these impacts on the number of non-tariff trade barriers imposed by the United States on China. And robustness test is carried out by lagged explanatory variables, Probit regression of replaced explanatory variables, tail shrinking and extreme value elimination, etc. Finally, heterogeneity analysis is conducted from the perspectives of different types, severity, and stages in the political and economic relationship between China and the United States.

The main research results mainly include:

 (1) When the technical complexity of China's export products increases, the level of tariffs on China increases, the number of non-tariff trade barriers implemented by China to the United States increases, and the internal macroeconomic environment of the United States deteriorates, the United States will set more non-tariff trade barriers to China.

(2) The standard of the United States' "non-market economy" towards China is an administrative regulation under the China-US political and economic game, and the improvement of the degree of Chinese market industrialization cannot effectively reduce the number of non-tariff trade barriers imposed by the United States on China.

(3) The implimensions of non-tariff trade barriers by the United States to China has strong industry heterogeneity, and the United States has a higher degree of protection for its manufacturing and information technology services industries than basic industries such as agriculture, forestry, animal husbandry, and fisheries. In the face of the increase of the technical complexity of China's exports and the number of non-tariff trade barriers between China and the United States, the United States tends to set up more non-tariff trade barriers with export incentives to help domestic enterprises occupy a favorable position in international trade. In the face of the deterioration of the domestic macroeconomic environment, the United States is more inclined to set up more local subsidies and import restricted non-tariff trade barriers to stimulate domestic economic growth. On the whole, the explanatory variables had a greater influence on the number of more serious NTBs and less on the number of mild NTBs.