Because the infrared thermometer needs to measure the body temperature of the subject at close range in the Covid-19 epidemic, and the measurement accuracy is relatively low, the safety of the body temperature measurement is not high and the risk of misjudgment is caused. In order to improve the accuracy of human body temperature detection by infrared temperature measuring equipment, this paper studies the distance temperature compensation method to improve infrared temperature accuracy, and designs an infrared temperature measuring gun system with long distance measurement, accurate measurement and wide application. The system is designed with STM32F103 as the main controller, and AMG8833 infrared thermal imager sensor module, OLED display module, laser ranging module and buzzer are used as peripheral equipment. In order to improve the accuracy of temperature measurement, the temperature value of the infrared dot matrix collected by the sensor module of the infrared thermal imager is compensated for light perception and distance temperature, that is, the collected temperature points at different distances are processed by fast descending sorting method firstly, and then the temperature points at different distances are fitted by multiple linear functions, so that the temperature compensation after passivation of different distance sorting is realized. After many experiments and debugging, the error is great when the distance temperature compensation is not carried out, and the error of the temperature value after distance temperature compensation is very small compared with the reference temperature value, which can meet the accuracy requirements of human body temperature measurement and improve the accuracy of long-distance temperature measurement.