Abstract: A wide area network oriented service discovery mechanism is described in this paper. Discovery servers in wide area networks are organized into a tree structure with each server node saves the address of its neighbor nodes, namely its father, brothers and children in the tree. The transmission message of service request is appended certain forwarding information. By matching the received service requests with service repository, each node response the service request or deals with the appended information in it and forward it to one of neighbor nodes. Thus, service discovery in wide area networks can be achieved effectively.