Abstract: The rapidly growing credit derivatives market requires to value credit derivatives and poltfolios of credit risks, and how to measure the correlation between each credit risk is the key problem of valuation.In this paper, we introduce a new technology--Copula function to integrate single credit risk, and discuss how to use copula function to manager poltfolios of credit risks and value credit derivatives. Credit risks are the main problems for Chinese banks. Credit derivatives have a function to transfer credit risks, Credit derivatives market grows very quickly, they are sure to become a very important part of financial market. Study the valuation techniques for credit derivatives, design appwpriate derivatives for Chinese financial institutions, and seek useful methods to mangage credit risks are helpful to improve the benefits and asset quality of Chinese commercial banks.