The invention belongs to the field of service robots and artificial intelligence, and particularly relates to a robot knowledge graph node updating method based on voiceprint recognition. The method mainly comprises the following steps: starting voiceprint recognition, collecting voiceprint information of a target person, querying a local or cloud database, judging whether the voiceprint information is in a knowledge graph database or not, if not, adding a new figure entity, taking the voiceprint information as an identification tag, actively asking a target person to obtain basic informationof the target person so as to add a new triple instance, reasoning the relationship between the target person entity and other entities, distinguishing different character entities, and carrying out personalized man-machine interaction selection in a targeted mode. According to the method, character entities are distinguished through voiceprint recognition, so that a robot determines different entities in conversation with the robot, entity information is actively added into a personalized knowledge graph of the robot, new triples are continuously inferred in interaction, the relationship between the entities is updated, and the knowledge graph is perfected.