Industry-University-Research Collaboration （IURC） is an important means to enhance the effectiveness of the national innovation system. Exploring the role of scientific and technological human capital （S&T HC） in the function of IURC is one of the key measures in implementing the requirements of "education，S&T，and talent" integrated development. Building on existing research，this study proposed a threshold effect hypothesis regarding the role of S&T HC in IURC and regional patent scale （RPS），and employed an econometric model to conduct empirical analysis. Using panel data of 30 provincial-level regions in China from 2010 to 2019，the findings were as follows:（1） IURC does not necessarily increase RPS，and S&T HC plays a threshold effect in this process. （2）The innovative effects of IURC have an upper limit on the size of S&T HC，and only when the S&T HC is relatively small does it show a positive impact on RPS. （3） There is heterogeneity in the effect of S&T HC on patent size and substitutability between it and S&T financial capital. The article reveals the threshold effect of S&T HC faced by IURC. The policy implications include implementing IURC policies according to local conditions for local governments，and actively guiding the balanced distribution of S&T HC for the central government，in order to better leverage the efficiency of the innovation system.