In peer-to-peer (P2P) environments, a peer needs to interact with unknown peers for the services provided. This requires the trust evaluation prior to and posterior to interactions. This paper presents Trust2: a novel and dynamic peer trust evaluation model, which aims to measure the credibility of peers? recommendations, and thus to filter noise in responses and obtain more accurate and objective trust values. In our model, prior to any interaction, the trust value results from the evaluations given by other peers. Posterior to interactions, the trust values results from both other peers? evaluations and the requesting peer?s experience. In the aggregation of trust evaluations, the weight to the requesting peer becomes higher and higher. Meanwhile, during this process, the credibility of each responding peer?s recommendation can be measured round by round. This leads to the filtering of low credibility peers and the improvement of trust evaluations.