Abstract: As Web services have the characteristics of only providing interface documents, complex technical specifications and run-time transient change, it is still a difficult problem to automatically generate test data effectively. At present, there is less current research on testing operation sequence for stateful Web services. Moreover, the existing approaches take insufficient account of service behavior information and the dependency between operations, and are lack of effective means of test automation, which may lead to high cost and short of specific for the test data. In this paper, a test case generation approach is proposed based on EFSM model operation interface contract. This approach constructs the operation model according to the standard WSDL document to describe the interaction relationship between operations and then add semantic annotation for them. Based on EFSM model, the paper proposes an automated operation sequences generation method and finally obtain the test suite using operation interface contract. The experiment shows that the proposed approach can generate reasonable test suite for stateful Web service efficiently, which can enhance the fault detection ability and improve the efficiency of test cases compared with the existed approaches.