Intensive efforts are made in the Web services selection literature by these days mainly because of the overwhelming interest of the community in the services provided over the Web. In selecting best services, the non functional properties of such services are proven to be more and more important; these describe the Quality of service that is the key factor in the selection process.In this paper, we discuss a Web service selection based on both the context and the QoS ontology. We propose an architecture that makes an automatic selection of best service provider that is based on mixed context and QoS ontology for a given set of parameters of QoS. The key idea is to rely on multi dimensional QoS. Finally, some experiments are run so to demonstrate consistency and effectiveness of the proposed method.