In order to prevent the over heating defects of gas-insulated metal-enclosed switchgear(GIS) contacts and solve the problem of unable to measure the temperature of internal conductor in GIS by traditional temperature measurement, high-accuracy temperature detection of internal conductor in GIS based on infrared thermal imaging is proposed. Through a series of tests, the depth analysis of the optical path factors and the pressure of the SF₆ gas which have an impact on the accuracy of infrared temperature, the concrete relationship among the optical path factors, the pressure of the SF₆ gas and the measurement accuracy is gained. So is the compensation formula. According to the distance of the measured objects and the pressure of SF₆, a set of algorithm improving the measurement accuracy of infrared radiation thermometer to obtain the actual temperature of the contact measured is designed. It can combine with exact temperature compensation calculated by compensation formula. The final result of test shows that the infrared radiation thermometer with compensation algorithm can measure the temperature of the contacts in GIS more accurately.