Abstract: Ontology mapping is one of common solutions of the ontology heterogeneous．Similarity computation among ontologies is the critical step of mapping process．Aiming at the current problems,and for making a further improvement in similarity computation,this paper put forward a comprehensive approach．This approach involves several factors of concept,semantic,properties,instances and structure of the concept．For finding more useful similarity computation method,the paper introduced relativity and attribute theory．At the end,an experiment was used to prove this method can adapt the different scale ontologies,and also can improve the accuracy of the similarity．

Key words: Ontology,Ontology mapping,Similarity,Attribute theory