Abstract: In order to study the typical character of receiving light intensity signal in ground-to-satellite/satellite-to-ground short-infrared and medium-infrared laser propagation, based on atmospheric turbulence theory and phase screen method, the scintillation of power ratio in the receiving aperture was calculated under the condition of specific atmospheric coherent length. According to the statistical results, the difference of uplink and downlink atmospheric channel was discussed. The results show that the receiving signal intensity of downlink channel is one order of magnitude greater than that of uplink channel and the signal scintillation level of downlink channel is lower than that of uplink channel. Under the condition of moderate atmospheric turbulence, the receiving light intensity probability distribution function of downlink channel is logarithmic normal distribution, and the maximum probability point is corresponding to that under no turbulence condition, the maximum probability receiving light intensity of short-infrared and medium-infrared laser are 0.42%(1.315 m) and 0.26%(3.8 m),respectively.