The knowledge spillover effect of inventors’ 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 citation from Chinese listed enterprises, this paper investigates the impact of inventors’ mobility on knowledge spill-in effect. We find that the mobility of inventors has knowledge spill-in effect on source enterprises, which lasts 1-2 years. We also find that the mobility of higher performance inventor has more obvious effect on the knowledge spill-in. The mobility of inventors also has a more significant effect on the knowledge spill-in when the source enterprises are non-SOEs or the target enterprises are SOEs. Besides, we demonstrate that the mobility of inventors take 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 such a positive effect is different in different enterprise characteristics. This paper contributes to the current researches of human capital flow from the direction of the inventors’ mobility and knowledge spill-in, which also provides important practical enlightenment for enterprises to accumulate firm social capital and promote knowledge spill-in to improve enterprise innovation.