Negotiation protocol is one of the cores of agent-mediated automated negotiation in future electronic commerce. Nowadays, most of the negotiation protocols are hard-coded into agent. Thus agent can only use the single protocol during its lifecycle or go off line to be reprogrammed with another one. To realize a flexible approach that permits agent to negotiate with arbitrary negotiation mechanism, we propose an ontology framework. This framework comprises two levels: the abstract level and the implementation level. In the abstract level, an extended Colored Petri net (ECPN) is used to represent and verify the concepts and their relationships obtained from the requirement analysis phase; in the implementation level, these concepts and relationships are transformed into classes, properties and individuals using Prot?g?. Furthermore, the inconsistency, which may exist among these classes, properties and individuals, is tested using RACER and the tools offered by Prot?g?. At last, we create an API program for this ontology.