Aiming at the micro and static aspects of methodology limitations in Peer-to-Peer (P2P) network resources-sharing research and based on features like self-organization, dynamic and expandability of P2P network, this paper advances an evolutionary game model for resources-sharing mechanism in P2P network peers by employing evolutionary game theory, which can analyze the dynamic evolutionary process of the mechanism. The analysis results show that the network?s evolutionary direction is related to the players? payoff matrix as well as to the network?s initial state. Moreover, the key factors affecting the network?s evolution, i.e., cooperation profit, initial cooperation cost, resources differences among peers and the relative discount factors, are further studied respectively.