Abstract: In this paper,we choose the agency variables of the diversification of commercial bank business from the two dimensions of income diversification and asset diversification,and take 28 commercial banks listed in A-share market in 2006~2019 as the research samples.Through the establishment of dynamic panel data model,this paper studies the impact mechanism of business diversification on performance and risk-taking in China's commercial banks,and empirically tests the intermediary role of risk-taking in business diversification and performance impact.The results show that,no matter from the perspective of income diversification or asset diversification,business diversification is negatively related to the performance of commercial banks in China,and positively related to the risk-taking of commercial banks in China,but its effect varies according to the ownership structure.In the role of business diversification on the performance of banks,risk-taking partially or completely plays an intermediary effect.

Key words: commercial bank, business diversification, performance, risk taking