Web services are widely used thanks to their features of universal interoperability between software assets, platform independent and loose-coupled. Web services composition is one of the most challenging topics in service computing area. In this paper, an approach based on High Level Petri-Net model as dynamic configuration schema of web services composition is proposed to achieve self adaptation to run-time environment and self management of composite web services. For composite service based applications, in addition to functional requirements, quality of service properties should be considered. This paper presents and proves some quality of service formulas in context of web service composition. Based on this model and the quality of service properties, a suitable configuration with optimal quality of service can be selected in dynamic way to reach the goal of automatic service composition. The correctness of the approach is proved by a simulation results and corresponding analysis.