The temperature detection system of running gear is installed on the main line of urban rail vehicles, and infrared thermal imaging technology is used to realize on-line detection of abnormal temperature of key components of running gear (such as gearbox, traction motor, axle box, etc.). Through infrared image pattern recognition technology, the system can realize the location of key components, accurate identification of alarm position and early warning prompt. Compared with the traditional infrared axle temperature equipment, the system has the advantages of wide coverage and visual target, which provides convenient conditions for fault confirmation.