Abstract: With the development of the P2P(Peer to Peer) technology, it's important to judge the reliability of the request peer. One reputation-based evaluation model for P2P is introduced to calculate the reputation value of each peer while the process of P2P and judge whether the request peer is reliable. "hhe model combines the past experience with other's suggestions. Through the experiments, it is proved that the model not only is able to protect normal peers from malicious peers, but also improves the ability to resist the attack from groups of the malicious peers.

Key words: P2P, Reputation, Evaluation model