The security problem for Peer-to-peer (P2P) systems hasbeen gradually recognized as an important topic of P2P applications.Among existing solution for P2P security, how to establish trustrelationship among peers is a key problem in demand. This paperproposes a novel dynamical trust construction schema based on fuzzydecision and Extended automated trust negotiation (EATN). The presentedapproach adopts fuzzy trust graph to describe the trust information inthe P2P systems. Trust relationship among peers can be constructed bythe combination of the fuzzy trust graph, fuzzy path search algorithmand EATN. The relevant application case indicates the schema isfeasible. The simulations also show that the presented schema canimprove the interactive success ratio by enhancing the trustrelationship in the P2P systems.