Mining high-power flameproof battery charger, mainly used for vehicle battery charging on special equipment such as battery-type bracket trucks and shovel trucks, is an important power supply equipment to ensure the normal development of underground work, and must ensure its reliability and safety. According to the research of IGBT failure mechanism, the cause of IGBT bursting of the charger is found by the elimination method as IGBT overtemperature failure, and the verification method is first used to analyze and calculate the loss of IGBT module and the thermal resistance of the radiator during normal operation. When the charger works normally, the junction temperature of the IGBT module die can reach 139.5 °C, exceeding its safety limit temperature of 125 °C, which is the main reason for the explosion of IGBT, and then by optimizing the heat dissipation structure of the radiator, increasing its heat dissipation area, reducing the thermal resistance of the radiator, and finally calculating the junction temperature of the IGBT module die is 88.48 °C, the junction temperature of the IGBT module die is controlled within the safe temperature range, and after the actual use verification, no bursting accident occurs again, indicating that the problem of IGBT overtemperature failure can be improved by optimizing the heat sink.