An optimistic route decision method based on the reputation is proposed in structured P2P networks. The
reputation is evaluated by using the Beta reputation mechanism before the routing decision process. Meanwhile, the
confidence is introduced for some nods which have short-time lifetime, which makes the reputation more reliable against
the nodes with short lifetime. In the process of routing decision under P2P environment based on the Chord protocol, the
concept of the optimistic routing is proposed. Greedy selection and reputation based selection are integrated to achieve a
reasonable way to multi-path routing. Routing-decision takes into account two factors of the efficiency and the reliability.
Simulation results show that this method can reduce routing hops and improve the success rate of routing.