First on credit rating agencies’ important role in the asset securitization, the article analyzed the negative effects of credit rating agency moral hazard for asset securitization, and discusses the cause of the moral hazard of the credit rating agencies; Secondly by constructing a dynamic game payoff matrix of credit rating agencies, using evolutionary game theory the article analyzed three different kinds of evolutionary stable strategy of the rating agencies; At last the article suggested to build a reputation mechanism, ensure the independence of rating agencies, and strengthen the supervision.