With the initial applications of unmanned aerial vehicle technology in various fields, the infrared (IR) radiation characteristic of the UAV becomes an issue of mutual concern. In this experiment, the radiometric cali-bration of middle wave and long wave infrared detectors has been done firstly. The radiation characteristics of the UAV are measured while flying, and the temperature of UAV target is inverted by using single-band method, dual-band colorimetric method and dual-band method based on black-body calibration. Combined with the real measured data, the above methods are analyzed and compared. The measurement precision is analyzed and error source is given. The results show that radiation intensity of UAV is about 0.04 W/sr in middle IR wave, and 0.5 W/sr in long IR wave. Dual-band method based on black-body calibration can improve the precision of UAV temperature inversion greatly, the absolute error of temperature retrieval reduces to 2 K, and relative error is about 0.5%.