Infrared radiation of exhaust system seriously affects the defense penetration ability of infrared stealthy cruise missile.Firstly,the calculation model of the cruise missile exhaust system was established,and the flow filed was calculated under the cruising state.Secondly,based on reverse Monte Carlo method,one program to calculate infrared radiation characteristics was written,and then based on the program,infrared radiation characteristics of the detecting points around the exhaust system were calculated.Finally,the infrared imaging and the distribution of spectral radiation intensity were analyzed.The results show that the infrared radiation of the missile presents transitional characteristic from gas radiation at the front detecting point to solid radiation at the end detecting point and the infrared radiation intensity in 45 degree cone space is strong,the simulation of infrared radiation has an important military value for improving defense penetration ability of infrared stealthy missile.