Abstract: “Financial disintermediation” makes the traditional commercial banks embark on the road of business diversification, services diversification and income diversification, as well as attracts special attention to the systemic risk in the banking. This paper selects14 banks listed before 2008 as samples, and takes MES value as the proxy variable of the systemic risk to study the relationship between bank diversification and MES value. Meanwhile, the bank scale is used as the tool to distinguish the different types of banks. The results show that there are significant differences in the impact of improving the level of diversification of city commercial banks, small and medium-sized joint-stock commercial banks and large state-owned commercial banks on systemic risks: improving the level of diversification will increase city commercial banks′ systemic risk and reduce small and medium-sized joint-stock commercial banks and large state-owned commercial banks′ systemic risk; when banks adjust the diversified business strategy to stabilize systemic risk, three types of banks above should consider increasing the proportion of fees and commissions, in addition, small and medium-sized joint-stock commercial banks and large state-owned commercial banks should also consider increasing the proportion of equity earning.

Key words: commercial banks, diversification, systemic risk