The MODTRAN5 radiation transport model is advanced over earlier versions of the MODTRAN model. The spectral resolution has been improved from 2 cm-1 to 0.2 cm-1. To validate the precision of atmospheric molecular absorption calculated by MODTRAN5 band model, the atmospheric molecular absorption spectral transmittance is calculated by using the accurate line-by-line atmospheric transfer model (LBLRTM), then as a reference to the results of MODTRAN5. The results show that the MODTRAN5 coincides with LBLRTM at most cases, and the root-mean-square error (RMSE) of atmospheric spectral transmittance between the MODTRAN5 and LBLRTM is almost below 0.02. But at some spectral region, the difference can be over 0.03. As the largest difference occurs at 4.3 μm wavelength which is the border of strong absorption band of carbon dioxide, the RMSE is 0.0377.