The total atmospheric transmittance is an important parameter reflecting the optical properties of the whole atmosphere, which is of great significance in the study of laser atmospheric propagation, infrared radiative transfer and the engineering application of photoelectric systems. The measurement principle of laser heterodyne technology is introduced firstly, especially the principle and method of high-resolution measurement of the total atmospheric transmittance by using laser heterodyne spectroscopy, as well as the method of simultaneous inversion of the profile distribution and column concentration of water vapor. Then the high-resolution laser heterodyne spectrometers at 4.5 μm and 3.53 mum band developed by our research group, with 0.006 cm-1 and 0.002 cm-1 spectral resolutions respectively, are introduced, and the typical measurement results of the total atmospheric transmittance, water vapor profile distribution and column concentration in Hefei area with the two devices are also presented. Finally, the future development of laser heterodyne technology in photo-electric systems engineering is prospected.