Web services is a new bread of Web application; it is the core of SOA (Service-Oriented Architecture), in which there are three basic operations, i.e., Web Services publication, Web Services discovery, Web Services binding/invoking. Service discovery is a key process in the whole procedure. When users input keywords to look up Web services, the service discovery effect is usually influenced by the inaccurate expression of user's requirement and user's different interest. So, it's more and more important to research effective Web services discovery.In the area of information retrieve, there is a relative mature method which utilizes user interest model to improve the efficiency of retrieve and realize individual retrieve. On the basis of this method, this paper puts forward a service discovery method based on user interest model to advance the veracity of service discovery. It captures users' interest through creating user interest model and does the recommendation actively for users in terms of their interest. By which, the individual service discovery is implemented. Experiments have proved that this new method can comprehends users' requirements exactly and roundly. And it recommends the Web services which user interested in. so, the accuracy and efficiency of service discovery can be improved at some manner.The main contents of this paper are as follows:1. Proposes a user interest model based on subject tree. Meanwhile, introduces expression and update of the model particularly.2. Analyses the principle of VSM. And extends it, puts forward Web services vector space model (WSVSM). Moreover, it constructs user requirement vector space model (URVSM) combing user interest information and user request.3. After that, we research individual matching arithmetic. Do the matching between WSVSM and URVSM. And do ordering and optimization according to similarity, and filtrate the Web services that irrelevant to user interest. By which, we can receive the Web services that satisfy users' requirements.4. In the end, we establish experiment platform and prototype system. And compare traditional Web services discovery method and Web services discovery method based on user interest model in precision, QOS, and efficiency. Thereby, the superiority of new method is obvious.