Abstract: Trust relationship between participants is indispensable to set up in a large-scale distributed P2P file-sharing system. A novel trust model for P2P system based on advanced D-S theory of evidence is proposed in this paper to solve this problem, in which mathematic analysis and some measures are presented to defense against several malicious attacks. The experimental results show that, compared to the current some trust models, the proposed model is more robust on trust security problems and more advanced in successful transaction rate.