Abstract:study on a monitoring method of the faults of high voltage device. Research the measurement theory of infrared thermal imager about the faults of high voltage device. And design a judging method which bases on the relative temperature difference of high voltage device. Then design a software which recognizes the faults of high voltage device with the infrared technology. This software scan unusual point of the infrared picture on all sides, and then indent the faults of these device and feed back the faults information, according to the judging method. Last, do the simulation test about the faults of devices, and then identify the faults of current mutual inductor and voltage mutual inductor. The results state that this technology realizes the analysis ability automaly of the devices’ faults, and improve the work efficiency to monitor these devices. It helps to guarantee power grid moving safely.