Abstract: The main nonfunctional attributes of Web services were analyzed, and the QoS about the Web service affected by these attributes was discussed. The evaluation method of QoS for Web service was proposed, and QoS was regarded as one of the conditions selecting Web service for Web service composition. Web service composition model based on QoS was formed, and the effective composition of the Web service was realized by using the methods of selecting subsequent Web service. This composition Web service can meet not only the functional requirements but also the personalized service for users