Model semantics is the base of model reuse, interoperation and composition. For the deficiency in semantic expression of Base object model (BOM), Ontology Web Language (OWL) was applied to re-describe the BOM specification. And a BOM ontology model was established which might supply guidance for meaningful composition between simulation components in a higher level. The results of the experiment reveal that the BOM ontology model is suitable for describing syntax and semantic information of simulation component. A knowledge components based on the BOM ontology model can be quickly searched, matched and composed and will greatly improved the developing efficiency of the simulation system.