The invention discloses an assistant diagnosis and treatment system based on a knowledge graph. The system comprises a database, a patient information processing module and a diagnosis and treatment scheme push module, wherein the database is used for storing the medical knowledge graph, and the knowledge graph takes medical operations as nodes and takes the patient state between every two continuous medical operations as an edge; the patient information processing module receives information of a patient, extracts historical medical operations and patient state information and sends the historical medical operations and the patient state information to the diagnosis and treatment scheme push module; the diagnosis and treatment scheme push module acquires the knowledge graph from the database, matches the patient information with the knowledge graph according to the direction indicated by the edge in the knowledge graph, determines the position of the current state, in the knowledge graph, of the patient, and pushes a to-be-detected medical index and / or the next diagnosis and treatment operation based on the knowledge graph. By means of the assistant diagnosis and treatment system,the diagnosis and treatment stage of the patient can be quickly known, and a next diagnosis and treatment advice is given.