Against the backdrop of energy structure transformation， new energy vehicles have become a development trend，but maintenance and diagnosis are difficult. The application of electronic diagnostic technology in the maintenance of new energy vehicles has significant advantages. It can reduce human misjudgment and has the advantages of high diagnostic efficiency，high accuracy and strong prevention. Its technical types are diverse，including fault code diagnosis technology，which can determine faults based on fault codes. Data flow diagnosis technology determines faults by collecting data； Sensor and actuator testing technology， detection of sensors and actuators； Remote diagnosis technology breaks through the limitations of time and space for diagnosis. The application paths cover the diagnosis of power batteries， inspection of wear and tear， charging faults， etc. Circuit system diagnosis， analyzing faults such as short circuits and leakage； Drive system diagnosis， troubleshooting faults in drive motors， controllers， etc. In-depth research on this technology is of great significance for promoting the development of the new energy vehicle industry.