人力资本是影响地区经济增长和创新的重要因素，是当今各经济体竞相争夺和积累的资源，“人才争夺战”反映的就是国内外不断升级人才政策集聚人力资本的现象。但各地集聚人力资本的能力不同，导致人力资本在空间分配上不均衡。根据集聚理论的观点，人力资本在地理空间上的密集程度和在人口中的密集程度，会影响其作用发挥。但目前在相关研究中考虑空间因素的研究较少，且探讨人力资本对创新影响的实证研究也相对有限。本研究认为地理空间因素和人口结构占比会影响人力资本对经济增长和创新的效应，是导致目前一些研究发现不一致的潜在变量。基于此视角，本研究构建了包含地理空间和人口结构两个维度的人力资本密度变量，使用我国2003-2017年的省级数据，采用2SLS回归方法，通过实证分析探讨了人力资本密度对我国经济增长和创新的影响以及地区差异。得到如下主要结论：

      第一，人力资本密度、经济增长和创新产出呈现不断增长趋势。样本前期人力资本密度增长平缓，提升幅度较小，经过一段时间高校扩招的累积效应，后期增长速度大大提升。经济增长以相对稳定的速度不断提高，创新产出在增长过程中速度明显加快。与2003年相比，2017年全国人力资本地理空间密度增长了250.38%，人口结构密度增长了158.73%。就业人均经济产出增长了207.06%，每十万人均专利申请授权量增长了815.32%。具有先发优势的一些省（市、自治区）和东部地区提升速度更快，进一步扩大了与中部和西部地区的差异。
      第二，从全国整体来看，人力资本密度两个指标均促进了经济增长和创新，且达到统计性显著。2SLS回归结果表明，人力资本地理空间密度每提高1%，经济增长将提高0.06%，创新产出会增加0.43%；人力资本人口结构密度每提高1%，经济增长将提高0.38%，创新产出会增加0.47%。
      第三，人力资本密度对经济增长及创新的影响存在地区差异。在东部地区，人力资本密度的两个指标对经济增长和创新的影响都是显著为正，提高人力资本的集聚程度，可以促进经济增长，增加创新产出。在中部地区，人力资本地理空间密度对经济增长是负向显著影响，而人口结构密度是正向显著影响；人力资本密度两个指标对创新产出都具有显著的负向影响。在西部地区，人力资本密度两个指标对经济增长的影响都不显著，但地理空间密度对创新产出的影响是显著为正，而人口结构密度对创新产出的影响是显著为负。地区间的差异显示出人力资本密度对经济增长和创新的影响存在复杂的作用机制。
      第四，控制变量对经济增长和创新存在不同程度的影响。从全国整体来看，物质资本存量对经济增长具有显著正向的影响，但对创新的影响不显著；高等院校数量对经济增长和创新的影响都是显著为正。产业结构对经济增长的影响不显著，但正向而显著地影响了创新。R&D经费投入强度对创新具有显著为正的影响。
      基于以上发现，本研究提出如下政策建议：一是进一步扩大教育规模，深化教育改革，提升教育质量，通过发展教育这一“内生型路径”提高人力资本密度。二是完善劳动力市场制度，鼓励人才合理流动，促进人力资本高效聚集，通过人才引进的“外生型路径”加快提升地区人力资本密度，扩大知识溢出效应。三是加速产业结构升级转型，完善公共服务和社会管理水平，通过良好的经济和服务环境留住人才，用好人才，充分发挥人力资本的价值。四是尊重经济发展规律，充分发挥各地的特色优势，提升区域优势对专业人才的吸引力，实现与区域特色发展相适应的专业化人才集聚。

    Human capital is an important factor affecting economic growth and innovation. It is the resources that every economy competes for and accumulates. “The war for talent” reflects the phenomenon that human capital is gathered by continuously upgrading talent policies at home and abroad. However, the different ability of gathering human capital in different regions leads to the imbalance of spatial distribution of human capital. According to the theory of agglomeration, the concentration of human capital in geographical space and population will affect its function. However, at present, there are few researches considering spatial factors in relevant researches, and the empirical research on the impact of human capital on innovation is rare. This study considers that the spatial factors and population structure will affect the effect of human capital on economic growth and innovation, which is the potential variable that leads to some inconsistencies in the current research. Based on this perspective, this study constructs a variable of human capital density including two dimensions of geographical space and population structure. Using the provincial data of 2003-2017 in China, and using the method of 2SLS regression, this paper discusses the impact of human capital density on China's economic growth and innovation and regional differences through empirical analysis. The main conclusions are as follows:

   First, human capital density, economic growth and innovation output show a growing trend. In the early stage of the sample, the growth of human capital density is slow, and the increase range is small. After a period of cumulative effect of college enrollment expansion, the growth rate in the later stage is greatly increased. Economic growth has been increasing at a relatively stable rate, and innovation output has accelerated significantly in the process of growth. Compared with 2003, in 2017, the national human capital geospatial density increased by 250.38%, and the population structure density increased by 158.73%. The per capita economic output of the employed population increased by 207.06%, and the number of patent authorizations per 100000 people increased by 815.32%. Some provinces and eastern region with the first mover advantage have increased faster, further expanding the differences with the central and western regions.

   Second, both indicators of human capital density promote economic growth and innovation of the whole country, and achieve statistical significance. The result of 2SLS regression shows that for 1% increase in the spatial density of human capital, economic growth will increase by 0.06% and innovation output will increase by 0.43%; for 1% increase in the density of human capital population structure, economic growth will increase by 0.38% and innovation output will increase by 0.47%.

   Third, there are regional differences in the impact of human capital density on economic growth and innovation. In the eastern region, the two indicators of human capital density have a significant positive impact on economic growth and innovation. Improving the concentration of human capital can promote economic growth and increase innovation output. In the central region, the spatial density of human capital has a significant negative impact on economic growth, while the density of population structure has a significant positive impact; both indicators of human capital density have a significant negative impact on innovation output. In the western region, the two indicators of human capital density have no significant impact on economic growth, but the impact of geospatial density on innovation output is significantly positive, while the impact of population structure density on innovation output is significantly negative. The regional differences show that there are complex mechanisms of human capital density's influence on economic growth and innovation.

   Fourth, control variables have different effects on economic growth and innovation. From the whole country, the stock of physica capital has a significant positive impact on economic growth, but not on innovation; the number of colleges and universities has a significant positive impact on economic growth and innovation. The impact of industrial structure on economic growth is not significant, but it has a positive and significant impact on innovation. R&D investment intensity has a significant positive impact on innovation.

   Based on the above findings, this study puts forward the following policy recommendations: first, further expand the scale of education, deepen the reform of education, improve the quality of education, and improve the density of human capital through the "endogenous path" of education development. The second is to improve the labor market system, encourage the rational flow of talents, promote the efficient accumulation of human capital, accelerate the regional human capital density through the "exogenous path" of talent introduction, and expand the knowledge spillover effect. Third, accelerate the upgrading and transformation of industrial structure, improve the level of public service and social management, retain talents through a good economic and service environment, make good use of talents, and give full play to the value of human capital. Fourthly, we should respect the law of economic development, give full play to the unique advantages of all regions, enhance the attraction of regional advantages to professional talents, and realize the professional talents gathering that is suitable for the development of regional characteristics.