This paper investigates the impact of financial flexibility on corporate performance based on the financial data of A-share listed companies in Shanghai and Shenzhen from 2012 to 2021, and by introducing accounting conservatism explores its role in moderating financial flexibility and corporate performance. The results show that the financial flexibility of enterprise reserve can improve enterprise performance, and the promotion effect is more remarkable in large-scale enterprises and non-state-owned enterprises; accounting conservatism can enhance the positive impact of financial flexibility on corporate performance. Accordingly, enterprises should pay attention to financial flexibility from a dynamic perspective, enhance the awareness of reserve financial flexibility, and raise awareness of the importance of accounting conservatism, so as to improve enterprise performance and promote long-term development of enterprises.