To ensure the correctness of composite Web services described by semantic Web services markup language(OWL-S)

and to guarantee the high performance of the composite Web services

a generalized stochastic Petri net based method is proposed for modeling

verification and evaluation of the OWL-S process models. The transforming rules from OWL-S process models to generalized stochastic Petri net(GSPN)are given. The analysis of S_ invariant

T_ invariant and reachability of the Petri net are used to verify the soundness of the process models. Moreover

Markov chains of the models are constructed. Performances of the processes are analyzed in terms of steady state probability distribution of generalized stochastic Petri net. It is verified mathematically that the models are correct and reliable. Also the bottlenecks of composite Web services is found. It is believed that the method will support to the reconstruction

optimization and decision-making of the composite Web services.