Based on the samples of Chinese A-share listed companies from 2003 to 2019, this paper studies the impact of institutional investors’ heterogeneity on stock price crash risk from the perspective of portfolio. The results show that the willingness of institutional investors to participate in corporate governance is influenced by the investment portfolio. Supervisory institutional investors do not significantly increase the risk of stock price crash, but non-supervisory institutional investors significantly increase the risk of stock price crash. The influence mechanism test shows that unsupervised institutional investors increase the risk of stock price crash by increasing the degree of information asymmetry. Further research shows that, compared with other enterprises, non-supervisory institutional investors in non-state-owned enterprises and enterprises with low corporate governance levels have a more significant role in aggravating the risk of stock price crash. Taking portfolio as the starting point, this paper explores the asymmetric impact of institutional investors’ heterogeneity on the risk of stock price crash, and provides a theoretical basis for CSRC to guide institutional investors to actively participate in governance and reduce the risk of stock price crash.