The invention relates to the technical field of substation fault inspection, in particular to a fault diagnosis and positioning method based on a transformer substation inspection robot system. The transformer substation inspection robot system comprises a server side, a communication module, a main control module, a data acquisition module, a navigation module and a motion control module, whereinthe data acquisition module and the navigation module transmit acquired information to the main controller, the main controller transmits the information to the server side by means of the communication module and receives an instruction from the server side, and the main controller receives the information from a motion controller and can further transmit the instruction to the motion controller. The fault diagnosis and positioning method is high in algorithm accuracy rate, high in fault precision ratio and rich in fault information, and the position information can be precise to the centimeter level.