Purpose/Significance To construct the ontology model of breast cancer knowledge graph, and to realize the structured expression and visual display of breast cancer knowledge. Method/Processs Breast cancer knowledge is extracted and represented, and the ontology model of breast cancer knowledge graph is constructed by Protégé software. The model includes 5 types of entities including patient, basic information of patient, inspection, diagnosis and attribute value of inspection, and more than 10 kinds of relationships such as having, examining, diagnosing, belonging and so on. Result/Conclusion The graphical display of breast cancer knowledge helps to improve the public’s attention and understanding of breast cancer, and has a positive effect on the prevention and health management of breast cancer.