Atmospheric radiative transfer in the thermal infrared spectrum is influenced by various factors, and atmospheric transmittance is a critical parameter. Currently, researching atmospheric transmittance within 8-14 μm thermal infrared spectrum remains challenging because of numerous elusive input background parameters. Consequently, a simplified parameterization scheme for thermal infrared radiative transfer in satellite remote sensing is proposed. Using the moderate resolution atmospheric transmission (MODTRAN) model, the impact parameters of atmospheric transmittance were quantitatively simulated and analyzed, to identify key parameters, leading to the development of a MODTRAN-model-based simplified scheme. Atmospheric transmittance values calculated by the MODTRAN model and simplified scheme were compared and validated at the central wavelengths of the two thermal infrared channels of a medium resolution spectral imager-LL (MERSI-LL). The R² value exceeded 0.99, and the root mean-square error (RMSE) was below 0.007458, indicating high accuracy. The simplified scheme relies solely on the view zenith angle and water vapor column, eliminating the need for CO₂, O₃, and aerosol optical depth. Compared with the MODTRAN model, the simplified scheme reduces the number of input parameters and enhances computational efficiency. This study offers theoretical support for atmospheric correction of thermal infrared data.