Legacy systems are valuable assets for organisations. They have been evolving with new emerged technologies in rapidly changing business environment. Web Services technology and Service-Oriented Architectures (SOA) are rapidly developed and widely supported. It is a very efficient way for developers to reuse existing core business in a legacy system. Reengineering a legacy system to provide Web Services is a great challenge. A tool was developed and called Web Services Wrapper (WSW). The WSW is composed of an Analyser and a Wrapper, which focuses on client-server legacy system with Microsoft .Net. A developer can generate Web Services and related source code according to the rules and constraints step by step with the help of WSW