<p>Numerous market phenomena show that social media can have an impact on investor behavior, but there is a lack of exploration in existing literature regarding the impact mechanism of social media on fund investment behavior and performance. This paper studies the impact of social media attention on fund net capital flow and fund performance, and further examines how it affects the relationship between fund net capital flow and fund rally. Fixed-effect model of fund-time two-way fixed effects is employed and the following main conclusions are drawn: firstly, a fund’s social media attention has a significant positive impact on the fund net capital flow; in large-scale funds, positive (negative) media attention has a positive (negative) impact on the fund net capital flow, and the impact of positive emotions on the fund net capital flow is greater than that of negative emotions. Secondly, fund net capital flow will have a positive impact on fund performance in the short term. Thirdly, social media attention may strengthen the positive correlation between fund net capital flow and fund rally.</p>