Abstract: To reduce the difficulty of binding a web service and improve the self-adaptability of service response, the concept of service cluster is proposed. A service cluster consists of a group of the services with similar functions and interfaces, by enlarging the grain of service requested, it can efficiently reduce the search space and improve the function compatibility. The algorithm to bind an appropriate web service in service clusters is presented. Logic service net constructed based on logic Petri net is put forward to describe the service flow based on service clusters. A judging theorem to test the soundness of a logic service net is also proposed in this study.