With the rapid development of interest-rate derivatives market in China， the impact of this market on bank credit is increasingly apparent. Based on panel data of 16 listed commercial banks from 2006 to 2011，analysis results show that the using of interest-rate derivatives produces significant substitution effect on traditional credit activities，that the ratio of the nominal capital of interest-rate derivatives held by banks to total assets increases 1 %，then the credit decreases 0.4%，however，the ratio of the nominal capital of interest-rate derivatives held to total credit increases 1%，credit decreases 0.26%. The substitution effect of interest-rate derivatives on traditional credit business of banks is conducive to optimizing China’s financial structure and further pushes forward healthy development of financial system. Thus，China should actively develop interest-rate derivatives market of China and use interest-rate derivatives to perfect monetary policy.