Current unstructured peer-to-peer (P2P) systems lack fair topology structures, and take no consideration for vicious action of peers. The mainly reason is that the topologies are not sensitive to peer’s trust, and take no consideration for the trust computation of different domains. First, a domain-based P2P trust model is presented in this paper. Then, based on the trust model, a peer-level protocol for forming adaptive topologies for unstructured P2P networks is proposed. The protocol aims at the topologies evolution of embodied domains, and makes good peers locate good position and bad peers locate bad position in the corresponding domains, which guarantees the impartiality of topology. On the other hand, the protocol can restrain the vicious action of peers effectively, and also has the incentive capacity, which encourages peers to provide more authentic services in order to get more return on services. Analysis and simulations show that, compared with the current topologies, the resulting topologies are more efficient and more robust on security problems.