Abstract: In order to solve the problems such as low efficiency of rectification and incomplete identification of safety hazard in coal mine, we present a method of constructing safety hazard identification system based on ontology. By analyzing the knowledge of the safety hazard in coal mine, the hierarchical structure of the safety hazard is established, the object attribute and the data attribute of the class are defined, and the ontology of safety hazard is formalized and stored by Protégé 4.0 software. On this basis, the safety hazard investigation and identification system is constructed, and the main function of the system is realized by using Java. The system solves the problem of the heterogeneity and reuse of safety hazard data, improves the utilization rate of safety hazard knowledge.