Abstract: This paper introduces both ratio of non-interest income to operating income and diversification index to study the impact of non-interest income on city commercial banks’performance. Based on a panel data of 23 large-sized city commercial banks in China from 2008 to 2013，we investigate effects of the non-interest income on bank performance by using panel data model empirical methods. The results show that the proportion of non-interest income and diversification is benefit to improve city commercial banks’performance.Large-sized city commercial banks may reduce the dependence of profitability on the interest by developing intermediary business. Policy recommendations of diversification are proposed on the basis of rapid development of capital market and the development trend of bank’s intermediary business. Large-sized city commercial banks should focus on strengthening newly developing and high value-added intermediary business to broaden source of intermediary business income and optimize income structure. At the same time，large-sized city commercial banks should promote information technology and strengthen talent support to keep sustainable development of intermediary business.

Key words: non-interest income, city commercial banks, operating performance, random effect panel data model, net interest income