Abstract: The interbank business of commercial banks has gradually evolved from traditional credit lending to credit like business. Some banks carry out regulatory arbitrage and risk assets listing through interbank business. The rapid development of interbank business interferes with the original monetary policy transmission system, and even changes the risk-taking channels of commercial banks.Using the data of 25 A-share listed banks from 2008 to 2018, this paper analyzes the impact of interbank business development on bank risk-taking in both theoretical and empirical aspects.Theoretically, interbank business can improve the level of risk-taking of banks and strengthen the channels of risk-taking of monetary policy, and the above-mentioned effects are accompanied with heterogeneity for different banks.The empirical results verify the hypothesis of theoretical deduction: the development of interbank business is positively related to the level of risk-taking of banks, and has a strengthening effect on the channel of risk-taking of monetary policy banks; interbank business has a limited impact on the level of risk-taking of large banks, but has a strong positive correlation on the level of risk-taking of joint-stock banks and small and medium-sized banks.By analyzing the risk-taking channels of monetary policy, the small and medium-sized banks are more sensitive to monetary easing, and their inter-bank business development has a strong correlation with monetary easing. According to the above research conclusion, the regulatory policy should pay more attention to the guidance of interbank business development under the hierarchical structure of the banking system, especially for joint-stock banks and small and medium-sized banks, it should gradually guide the banks with high proportion of interbank business to compress interbank assets, encourage commercial banks to return to their original sources and support the development of the real economy.

Key words: interbank business, monetary policy transmission, bank risk-taking channels, heterogeneity