Abstract: For traditional SIP service implemetation,severs work individually,and there exist problems such as low availability of resources and high cost of information update.Based on the idea of peer-to-peer computing,we built a Chord overlay with all SIP servers,modified the route table of Chord,distributed replicas with equal-distance address Hashing method,and thus proposed an improved multi-server cooperation method.Theoretical performance comparison was made among our new method,traditional individually-working method,and Chord-based cooperation method.Simulation results showed that our method can guarantee high success ratio of query and speed of forwarding,and decrease overhead of network traffic.