Human resources are an essential foundation for long-term economic growth and social progress in developing economies. The question of how to deepen the reform of the talent cultivating system and stimulate the strategic value of human resources has always been one of the heated issues that the government and entrepreneurs pay attention to. However, previous literature focuses on investigating the direct role of individual education investment or macro-policy guidance but overlooks the indirect spillover effect caused by talent accumulation inside the organization. Therefore, there is a literature gap on talent accumulation at the micro-organizational level, leading it difficult to reveal the mechanism of human capital in enhancing the core competitiveness of firms. Given this, this study takes the endogenous growth theory as the core clue, integrating the perspectives of human capital externality and capital-skill complementary, and systematically analyzing the impact of postdoctoral workstations on the human capital in firms.The research data are compiled from two sources. On the one hand, we start our sample construction with a comprehensive list of Chinese A-share listed firms from 2011 to 2019. Firm-level labor employment structure data are retrieved from the WIND Stock database. On the other hand, to form a list of firms that are allowed for setting up a postdoctoral workstation, we manually collect information on the postdoctoral program from the website of the Ministry of Human Resources and Social Security. After merging with the above databases, our initial sample consists of an unbalanced panel of 12,134 firm-year observations. Then, we construct a PSM sample with 8,292 observations from 1,438 listed firms for the DID estimation.There are four main findings in this study. First, the postdoctoral workstation significantly promotes the upgrading of human capital in firms, which boosts the relative employment of skilled labor to rise by about 5.7% on average. Second, the channel test shows that the establishment of postdoctoral workstations has a direct impact on both the increment and stock of human capital and accomplishes the optimization level of human resources by promoting the “structural aggregation” and “learning-by-doing” effects on human capital. In addition to these direct effects, postdoctoral workstations also improve the quality of independent research and development in firms, and thus indirectly activate the skilled labor to play the role of “innovation carrier” to meet the needs of industrial upgrading. Third, further analysis indicates that employee stock ownership plans, urban vocational education, and industry competition will make the main findings more pronounced. Fourth, the postdoctoral workstation has a spillover effect, and its human capital upgrading effect can significantly promote production efficiency, financial profitability, and firm value in capital markets.This study contributes to the existing literature in several ways. First, it provides an integrated insight into the increment and stock of human capital to investigate the underlying mechanism of how postdoctoral workstations affect human capital in firms. Hence, it expands the research perspective of the driving factors of human capital upgrading at the micro-organizational level. Second, it links highly-educated talents with highly-skilled talents together, revealing the unique role of postdoctoral workstations in promoting the value spillover of skilled labor, which is a response to the academic community’s call for research on the synergistic aggregation effect of human capital at the organizational level and its strategic value. Third, as this study also examines the moderating effect of heterogeneity among different firms, cities, and industries, the conclusion can help entrepreneurs understand how to develop human resources efficiently and shed additional light on policy-making.