The knowledge spillover effect of inventor mobility is bidirectional, and there is also a knowledge spillin effect on the source enterprises. Based on a matched dataset of inventors and patent citations from Chinese listed enterprises, this paper investigates the impact of inventor mobility on knowledge spillin effect. The paper finds that the mobility of inventors has a knowledge spillin effect on source enterprises, which lasts 12 years. Further, the mobility of higher performance inventor has a more obvious effect on the knowledge spillin. The mobility of inventors also has a more significant effect on knowledge spillin when the source enterprises are nonSOEs or the target enterprises are SOEs. Besides, it is demonstrated that the mobility of inventors takes effect mainly through the following channels: Cooperative R&D between source enterprises and target enterprises, and a favorable network position in the inventors’directed mobility network. Additional analyses suggest that this positive effect varies based on different enterprise characteristics. This paper contributes to the current research on human capital flow from the direction of the inventors’mobility and knowledge spillin, providing important practical insights for enterprises to accumulate firm social capital and promote knowledge spillin to improve enterprise innovation.