This paper constructs a theoretical model of social media use, knowledge stock, innovation atmosphere and enterprise innovation performance. The purpose of this study is to explore the impact mechanism of social media use on corporate innovation performance. Based on 380 survey samples, this paper uses SEM method to test the hypothesis made in this paper. The results show that: both external-oriented and internal-oriented social media use have a positive impact on enterprise innovation performance; knowledge stock plays an intermediary role in the relationship between external-oriented social media use and enterprise innovation performance; knowledge stock also plays a mediating role in the relationship between internal-oriented social media use and enterprise innovation performance; finally, the moderating effect of innovation atmosphere has been verified.