Abstract: Atmospheric scattering is one of the factors influencing the energy attenuation of infrared radiation in the atmosphere. Considering the variation in the aerosol density with altitude, the calculation method of atmospheric scattering transmittance is developed for the horizontal homogeneous transmission and oblique transmission integrating the atmospheric visibility parameters. In the case of horizontal homogeneous transmission, the average transmission method of atmospheric aerosol scattering transmission in the mid-long wave band is calculated by performing conventional integration. Compared with the result of the engineering calculation formula using the median wavelength, the engineering calculation formula is shown to have sufficient engineering accuracy. For the case of slope propagation, a slope engineering calculation formula for infrared atmospheric aerosol scattering transmittance was obtained by integrating the altitude. The effects of the altitude, waveband, and visibility on the atmospheric scattering transmittance are calculated and analyzed. This study has great significance for the establishment of an independent accurate atmospheric transmittance calculation model, the downward-looking detection performance of computer-borne detectors for infrared targets, and provides a good understanding of the factors influencing atmospheric aerosol scattering transmittance.