Market economy is the credit economy and principal of credibility is the foundation of market mechanism. With the development of economic reform, it is well concerned that discredit order of the society has become one of serious social problems which enhance the transaction cost of society. By using games analysis, reasons of discredit are studied based on personal behavior models under governmental regulation. According to the result that discredit is the result of personal choice under the existed institution, we should establish social credit management system to deal with the discredit based on credit information supplied by the independent third-part organization.