In recent years, web services have become a prominent paradigm for distributed systems and electronic services. Web service provides a framework for application-to-application interaction based on existing standard web protocols and XML technology. The enhanced features of web service such as interoperability, dynamic discovery and composition brings new challenges in testing of web services. In this paper, we propose a framework for optimization of web service regression testing with respect to different service evolution scenarios. First, we have identified the changes using a change detection algorithm on the generated operation tree of both original and modified WSDL files. Next, a dynamic forward slicing algorithm is used to select only the modified and the affected parts of the web service. Further, we have used an optimized regression test algorithm which gives us optimized test cases.