The invention provides a knowledge graph establishing method and device based on medical and health big data. The method includes the steps of establishing a data model for defining at least one entity, at least one property corresponding to the entities and at least one relation, for all medical data sources, collecting entity type field content, property type field content and relation type field content in the current medical data sources, executing corresponding filling on the collected field contents based on the data model to establish knowledge graphs, and for all the established knowledge graphs, when a first field content in another knowledge graph is consistent with the second field content in the current knowledge graph, fusing the two field contents. The knowledge graphs are established based on the medical and health big data, redundant data is removed through alignment and fusion of the knowledge graphs, the information association degree of the established knowledge graphs is high, and the knowledge graphs established through the method can make obtained individual information more comprehensive.