Abstract:he causes of CNC equipment fault are complicated, concealed and difficult to be investigated. To realize the accumulation, organization and sharing of the historical cases of CNC equipment fault, the method of constructing vertical knowledge graph was put forward. Firstly, the data-driven incremental construction technology is used to build CNC equipment fault ontology model. Then the data-mapping mechanism based on mode, which transform related database data into resource description framework data for storage, is proposed. Based on this, the visualization, management and application of the knowledge graph are realized. Finally, knowledge graph construction system in CNC equipment fault field is developed and the validity and rationality of the knowledge graph construction method is verified. Practice has proven that the construction of knowledge graph to the fault data accumulation, organization, fault reasoning and fault diagnosis on the field of CNC equipment fault has some guiding significance.