Green credit is a credit policy formulated by the government to curb highly polluting industries. The development of the policy is necessarily related to its business performance. According to the social responsibility report disclosed by banks， this paper collects the panel data of green credit business in detail issued by 12 banks from 2010 to 2017 for theoretical analysis and empirical research. The results prove that the impact of green credit business on the profitability of small and medium-sized joint-stock commercial banks is not significant， and it will reduce the profitability of large state-owned banks， but the increase of total loans will improve the profitability of banks as a whole. The scale of green credit improves asset quality of large state-owned banks. The larger the scale of credit， the lower the non-performing loan ratio. There exists a significantly inverted U-shaped relationship between the scale of green credit and asset quality of medium-sized joint-stock commercial banks. Non-performing loan ratio increases first and then decreases with the expansion of the scale of green credit.