This paper uses the quarterly data of China's listed commercial banks from the first quarter of 2009 to the fourth quarter of 2022 to study the impact and mechanism of commercial banks'ESG performance on profitability.The results show that ESG performance of commercial banks can significantly improve profitability.The results of mechanism test show that ESG performance of commercial banks improves profitability by reducing interest payment cost and improving asset quality.Further research finds that the three pillars of ESG performance(environmental,social and governance)of commercial banks have significant differences in their impact on profitability.Governance performance improves the profitability of commercial banks,while environmental performance reduces the profitability of commercial banks to some extent at this stage,and social performance does not show a significant impact on the profitability of commercial banks.The ESG performance of commercial banks has a more significant impact on profitability in national commercial banks and commercial banks with low loan-deposit ratio and high savings deposits ratio.