With the wide application of ontology in data integration, the concept of ontology-oriented similarity calculation became a hot issue of concern. In view of the problems that current domain ontology concept similarity calculation processes are complex, this paper proposes a concept of ontology similarity calculation method based on tree structure. The thought of this method is that through adding virtual nodes and restructuring, refactoring ontology tree, and then comparing and mapping object properties, at last, the computation of the concept of ontology semantic similarity results are obtained. The experimental results show that the method is effective to use the concept of ontology semantic information, reasonable calculation results are obtained, it can also simplify the calculation process.