Based on data from 2015 to 2021, a two-way fixed effects model was used to investigate the impact of post-mixed-ownership reform on corporate profit by examining changes in the equity structure, which serves as a reference for the reform of competitive state-owned enterprises. The results indicate a positive correlation between increased equity depth and profitability, with moderate equity concentration also positively influencing profits. Heterogeneity analysis suggests that the reform's effectiveness is higher in the eastern region. Robustness tests support the conclusion that, overall, mixed-ownership reform positively affects corporate profitability by increasing equity depth and achieving moderate equity concentration. It provides both theoretical and empirical support for mixed-ownership reform and offers valuable insights for companies aiming to enhance their profitability in practice.