It is very important to reform the RMB interest rate mechanism for China’s market economic system and banking competition mechanism. According to the 2003-2012 panel data of 14 national commercial Banks, respectively using the fender index and the DEA method to measure of market competition and scale efficiency, this paper study the influence of market competition on bank performance under the interest rate marketization. It argues that:①in the short term,the enlgargement of spreads improves bank performance.②the u-shaped relationship is between the market competition and bank performance.③the influence of scale efficiency value of bank performance is significantly positive correlation.