Abstract: Innovation has an important influence on the long-term stable operation of enterprises and the national economic development. The linear relationship between corporate financing constraints and innovation performance is investigated, and the external factors of mitigating the negative effects of financing constraints from a macro perspective are explored by prior empirical studies. However, the seemingly contradictory findings from the relatedstudies indicate that there can be the non-linear relationship existing between enterprise financing constraints and innovation performance, which is still under-explored in extant literature. Moreover, although various external factors have been found to mitigate the negative effects of financing constraints in extant studies, it is still difficult for enterprises to follow the implications in practice accordingly because most of these factors are actually beyond their control.
In view of these, based on a comprehensive discussion of the positive and negative effects of financing constraints on corporate innovation, it is proposed that there may be an inverted U-shaped relationship rather than a simple linear relationship existing between corporate finance constraints and their innovation performance. Further, from a perspective of human capital social network, the potential moderating effect of corporate's centrality in the network on the relationship between financing constraints and corporate innovation is explored.
Specifically, to test ourpropositions, individuals' turnover records from LinkedIn (China) are obtained, and a corporate-level talent mobility network based on the records is built. By further incorporatingthe finical data of listed companies, a panel data set with a time interval of 2000-2014 is obtained. The results demonstrate that there is a significant inverted U-shaped relationship between corporate financing constraints and innovation performance (β=-0.009, p<0.05), and the human capital social network exert a positivemoderating effect on the relationship between corporate financing constraints and innovation performance (β=0.236, p<0.05). The robustness tests consistently show that the resultsabove-mentioned are valid.
Our understanding of the relationship between financing constraints and corporate innovation can be enriched and the extant literature is extended in the following aspects:1)the research on the related issues is reconciled by unveilingthe nonlinear relationship between financial constraints and corporate innovation. 2)By adopting a perspective of human capital social networks, we find the important role of corporate centrality of such network as a moderator of the relationship between financing constraints and corporate innovation is found. Theories and methods of human capital social networks are expanded to the field of innovation research, and a new direction for future research to identify more relevant factors in moderating the impacts of financing constraints is proviede. Some important managerial implications are also provided based on the findings.

Key words: financial constraints, innovation performance, employee mobility, social network, panel data