Abstract: The process formal semantics of OWI-S is a key issue in the research on semantic Web service. This paper analyzed the current work and existing problem of research on OWL-S process formal semantics, and proposed an extended Colored Petri net, which is called Process Model net(PM net) , to model and analyze the process formal semantics of OWL- S. According to the characteristic of OWL- S process modcl,PM net extended the transition and fire rule of basic CPN, so that, the atomic process, composite process and data flow of OWL-S process model can be mapped to PM net equally. The method to check consistency of OWL- S process formal semantics based on PM_net was also introduced. The work of this paper provided reasonable theroy foundation for the evolution ofOWL-S, semantic Web service composition and verification.

Key words: Process formal semantics, OWL-S, Process model net, Colored Petri net, Ontology evolution, Semantic Web