In order to meet the detection requirement of aerial target in the complex background, according to the motion characteristic of aerial target in actual situation, the radiation characteristics of the target in different flight altitude and detection elevation were analyzed, the atmospheric radiation and attenuation data were calculated based on MODTRAN, and the infrared imaging simulation system was established based on the 3D model, the thermal radiation and reflection model of aircraft. Results shows that in mid-wavelength, the infrared radiation of the target plume is much stronger than that of the skin. In the long-wave band, the infrared radiation of the skin is stronger, and the corresponding simulation image has more details, the infrared imaging is still good, although infrared radiation of the plume is weakened. Under the same detection conditions, the higher the location, the thinner the atmosphere, so the detectable distance of the detector will become longer. The infrared radiation characterization and simulation system building can provide a reference for shortening the development time of infrared detector and further determining the detection spectrum and system solution.