Web services have gained popularity in recent years and provide a new model of web,which facilitates interaction of scientific and business applications through the Internet.More often,several services with similar functionality are available from a large and changing number of service providers.Quality of Service(QoS)is the dominant factor in service selection and is of great importance to users.In this paper,we propose a model for QoS measurement and web services selection.The model consists of QoS model,QoS monitoring,QoS comparison and service selection with a QoS feedback mechanism.The most suitable service is to take into account the agreed QoS,monitoring is done during invocation phase and if any deviation is recorded,next suitable service is selected.Finally the model is proved to be feasible and effective by simulation experiments. Web services have made popularity in recent years and provide a new model of web, which facilitates interaction of scientific and business applications through the Internet. More often, several services are available from a large and changing number of service providers. Quality of Service (QoS) is the dominant factor in service selection and is of great importance to users. This paper, we propose a model for QoS measurement and web services selection. The model consists of QoS model, QoS monitoring, QoS comparison and service selection with a QoS feedback mechanism. The most suitable service is to take into account the agreed QoS, monitoring is done during invocation phase and if any deviation is recorded, next suitable service is selected. Finally the model is proved to be feasible and effective by simulation experiments.