The invention discloses a vehicle fault online diagnosis system. The system comprises fault information collection equipment, intelligent information display equipment, fault information recording equipment, fault information alarm equipment and GPS positioning equipment. The system is scientific and reasonable in structure and safe and convenient to use, enables people to know a vehicle fault inadvance, avoids a sudden traffic accident of a vehicle in the traveling process and lowers economic loss; and people can observe and understand vehicle fault information more visually, therefore, it is convenient for people to further analyze and determine the fault information, and the diagnosis accuracy of the vehicle fault information is improved.