Based on infrared radiation theory and infrared thermal imager temperature measurement principle,a comprehensive radiation temperature inversion method combining infrared image gray level with target temperature,environment temperature and integral time is proposed to solve the influence of high temperature radiation source and environment temperature on infrared temperature measurement,and improve the temperature measurement accuracy of infrared thermal imager under extreme working conditions.This method realizes the decoupling of ambient(lens)temperature and scene temperature parameters,and can independently predict the changes of detector response caused by the changes of each parameter.Firstly,the data calibration of infrared thermal imager is carried out,in which high precision surface source blackbody is generally adopted.Then,by calculating the radiation luminance of surface source blackbody and using the linear relationship between blackbody radiance and blackbody gray,the relationship between blackbody temperature and the gray value of blackbody image is fitted,and a large range temperature inversion matching model of the whole ambient temperature and the whole integral time is established.Finally,in the laboratory environment,the thermal imager and the temperature inversion model based on gray level are respectively used to measure the temperature of the detected target.The experimental results show that the inversion model achieves relatively good results in laboratory environment.