The aim of web service verification is how well the web service conforms to the WSDL specification and it is the key of web service popular adoption at present. In web service testing, the adequacy of test is the essence to verify if the software satisfies WSDL specification with the increasing complexity and applications of web service. This paper presents a systematic approach for web service testing based on fault-coverage which is intended to be used for service testing automation. In this method, HPNs representing operations are produced from WSDL specification after parsing process. A graph transforming from the HPN representing a web service is used to generate the adapted UIO sequence, then test sequence based on the adapted UIO sequence is given to acquire high fault coverage. Constraints-based test data generation for service testing getting sufficient test data to kill mutant program is presented in this paper. Constrains are departed to two kinds: user-defined and policy based on the syntactic and semantic analysis for WSDL specification. At last, we applied a test script language based on XML to effectively describe the test sequence. The test sequence and constrains for test data are expressed by this language. The test scenario is built on this formal language. The prototype system based on above method automating the web service test is developed in our lab.