To solve the problems we now encounter in web mining, We first propose a new distributed computing strategy——web service. It suggests building a web mining system based on web service, which can share and manage semi-structured data from heterogeneous platforms. Moreover, the system can integrate the mining services and algorithms, improve the efficiency of web mining, and make the mining results easier to access. We also conduct an experiment on selecting useful words to simulate the realization of the web mining system on the Microsoft.NET platform, which demonstrates the importance of Web service in Web mining.