Abstract: A numerical method was developed for predicting the infrared radiation characteristics of UAV by combining a high precision resolution Computational Fluid Dynamics (CFD) technology of Navier-Stokes equations and discrete transfer method of spectral radiation intensity equation. Firstly, the skin aerodynamic heating performance, engine exhausts temperature and species mole fraction distribution of UAV were calculated by CFD method. Then, combining with discrete transfer method, comprehensive analysis of infrared signal characteristics of main radiation source, such as skin, nozzle and plume, were performed under different infrared detecting sensitive bands. As a result, the effects of the UAV geometric features, the engine nozzle configurations and plume flow field distribution on infrared radiation with different parameters were analyzed. Finally, some valuable conclusions for infrared stealth design of UAV were obtained.