High temperature exhaust plumes of warship power system is an important source of infrared radiation. In this paper, the flow field of ship exhaust plumes was calculated based on CFD methods. Then, a calculation method of high temperature exhaust plume′s infrared radiation was obtained by utilizing the C-G approximation method laced on a narrow-band model. Based on this model, the influence of the combined speed on the flow field and the infrared radiation of ship exhaust plumes were analyzed. According to the simulated result, the combined speed has an obvious influence on the shape and distributing area of the exhaust plumes. In addition, when the combined speed increased, the average radiation intensity of ship exhaust plumes decreased about 48.1 percent in the mid-wavelength infrared range. The physical factors for the error of the simulation model are discussed preliminarily.The carbon particles caused by the incomplete combustion have a significant impact on the plumes′ infrared radiation transmission.