Based on the analysis of the difference among the actual atmospheric environment parameters and the target-background radiation intensity, the monthly distribution characteristics of atmospheric transmissivity and target-background contrast in east China sea area and northwest area at 3.9 μm and 9.2 μm are analyzed by the MODTRAN mode. In order to study the comprehensive influence of actual atmosphere and aerosol on target-background radiation transmission, a further research about the influence of aerosol effect on the distributions of atmospheric transmissivity and target-background contrast at 3.9 μm and 9.2 μm is carried out combined local region monthly average environmental parameters. The result shows that the atmospheric parameters of atmospheric temperature and water vapor mixing ratio have influence on the distributions of atmospheric transmissivity and target-background contrast. The target-background contrast in east China sea area is always lower than that in northwest area. The target-background contrast at 3.9 μm is not only lower than that of 9.2 μm in the two areas, but also suffers more aerosol attenuation. Therefore, the 9.2 μm is highly recommended as the working wavelength in the target identification.