Nowadays the reputation has become an unavoidable issue in the development of e-commerce.In C2C business model,the reputation is regarded as the basis of transactions and it is directly related to the safe and effective of transactions.Based on the interest of the sellers,the paper analyzed the evolution of reputation in C2C with the game theory, then it proposed the conditions for both penalties and trust.Some conclusions are obtained as following:When the sellers entry market,the promise and punishment policy play the important role to establish reputation.As time goes by,for those sellers who have some reputation,the trust policy is more important.