Abstract: The invention discloses a vehicle fault reasoning method based on a knowledge graph, includes: constructing a knowledge graph of a vehicle fault; obtaining a question statement (QS) from user; performing question classification on the QS by TextCNN to obtain a classification result; marking a training QS by using an NER data marking manner and training an entity extraction model based on a sequence marking result; generating a vehicle fault class by a decision tree model for extracting the QS and searching for an answer in the knowledge graph; and performing question template matching based on the classification result and the answer and substituting the answer into the question template to obtain an answer statement. A question answering system constructed by the method includes word processing, question classification, question template matching, and answer generation, which helps the user judging a fault problem of vehicle, and searching for related knowledge about vehicle fault.