Abstract: From the point of software implementation, and considering the question that how Petri network of web service composition can be automatically generated, the method of web service registration based on Petri network was proposed in this paper in order to make Petri network theory and method widely applied in service composition. Firstly, on the basis of the ontology which had been established, the parameter names of the web services were unified. Secondly, according to the input and output of web service, the Petri network could be drawn. Meanwhile, the semantic information was added to the places in Petri network of web service to create the PNML+OWL file. Finally web services’ related information and PNML+OWL file were transmitted to the server-side to be registered and saved. This method can laid the foundation for the automatic generation of Petri network of web service composition, and is further illustrated in this paper, using the flight ticket query service and tourism composite service.