Abstract: To resolve problems of OWL and UML such as unclear hierarchy or relevant visible model notation absence etc.Similarities and differences between UML and ontology description languages are analyzed.On the basis of this,a metamodeling of ontology modeling language is brought forward and an ontology modeling tool set up based on UML(UBOM).Compared with other relative devices.The notion system of the UBOM is more clear and has its integrity.Furthermore,UBOM can support not only DAML and OIL but OWL,and accords well with the semantics of ontology model.