Abstract: Infrared temperature measurement, as an important method of live detection, is used to detect potential safety hazards in the operation of power equipment in advance, and to safeguard the safe operation of the power system. In this inspection, a rare phenomenon of complete breakdown of the upper section of a 220 kV bus lightning arrester was discovered through infrared temperature measurement, causing abnormal heating in the lower section with a phase to phase temperature difference of up to 4.6 K. This is a critical defect, and timely power outage replacement was carried out to ensure the safety of the equipment and power grid. After replacement, the correctness of the analysis was verified through power outage testing, and it was proposed to improve the timeliness of monitoring the operation status of lightning arresters by installing leakage current monitoring devices, strengthening inspections for data comparison, and other means to ensure equipment safety and power grid safety.