The study on spectral and spatial distribution characteristics of infrared radiation of plume is useful for the demand of detection or defense mechanism of aircraft. The absorption spectrums of gas molecule are obtained by Curtis-Godson approximation. The spectral and spatial distribution characteristics of infrared radiation of plume are computed by solution of radiation transfer equation. The plume radiation intensity of a certain observation direction is obtained by integral on all parallel sample lines of sight. The calculation is reduced by adoption of adaptive coordinates method. There is strong plume radiation in the two bands of 2.7 μm and 4.3 μm due to molecular emission bands of high temperature CO2 and H2O, while the radiation intensity in the two bands greatly decreases after atmosphere propagation. The plume spectrum distribution and radiation intensity vary versus the observation direction. There are two distinct radiation bands of 2.7 μm and 4.3 μm when observed from the front. When observed in the backside, the radiation is much stronger and the characteristic of selective radiation is not so clear.