A simulation study was made to analyze the effecting factor on the infrared radiation calculation for naval ship chimney using the mathematical model of the infrared radiation intensity.The simulation results indicated that there are three main effecting factors on radiation intensity,including thermal parameters of flue gas,radiative parameter of infrared radiation object and noises of environments.The ratio of specific heat has the most effect followed by emissivity of radiative object and noises.To reduce infrared radiation,it was necessary to confirm the ratio of specific heat,emissivity and depressing noise.