Ownership concentration is the main form of ownership structure. In order to explore the impact of ownership concentration on stock price, this paper empirically tests the impact of ownership concentration on stock price crash risk and its influence mechanism from a nonlinear perspective, using the data of A-share listed companies from 2003 to 2020. The results show that ownership concentration has an exponential positive correlation with stock price crash risk, and there are both "synergy effect" and "tunneling effect" in the process of ownership concentration affecting stock price crash risk, but the tunneling effect plays a dominant role. In addition, there is no significant difference in the impact of ownership concentration on the risk of stock price crash considering the eastwest regional heterogeneity, industry heterogeneity and firm heterogeneity.