Abstract: In order to achieve self-adaptation to run-time environment and self-management of Web service composition, an extended hierarchical Petri net is presented to reflect the feasible configuration scheme of composite service. Being different from related works, the dynamic configuration scheme and execution process of Web service composition can be reflected together in the extended model. Furthermore, a rapid QoS calculation strategy of composite service is presented. Some important QoS calculation formulas are presented and proved. Based on the extended model and the QoS calculation strategy, a configuration with optimal QoS can be selected dynamically. The QoS of composite service is improved. The soundness and correctness of the dynamic configuration method are proved by simulation results and corresponding analysis.