Efficient information sharing and exchanging are becoming increasingly important , but model heterogeneity hinder the communication and collaboration from different enterprises. To solve this problem, a semantic mapping method based on ontology structure graph is put forward in this paper. The requirement of model semantic interoperability among multiple enterprise model is analyzed , and model semantic interoperability is defined. Then, semantic clash between enterprise models is summarized and illustrated. Moreover, the formalization of semantic mapping rules is presented to support semantic mapping process from enterprise model to ontology. Besides, based on the description of ontology representation schema called ontology structure graph (OSG) and definition of semantic similarity function, semantic mapping process including model element choice, ontology elements selection, 3-level semantic matching based on OSG, semantic mapping rules generation , semantic mapping rules executing is illustrated in detail. Finally, the conclusions and future work are presented.