Abstract: The statistical characteristic of the three important factors which are fading probability, mean fading number and mean fading time of satellite-to-ground optical communication link subject to weak atmospheric turbulence is researched, and the influence of zenith angle, light wavelength and altitude of receiver on the satellite-to-ground laser link is analyzed by numeric simulation. The result of research shows either decreasing the zenith angle or increasing the detection sensitivity of receiver can improve the fading characteristic of laser link; the 1.55 m laser is more suitable for satellite-to-ground optical communication than 0.85 m and 1.06 m; the receiver should be established in the region with altitude higher than 2 000 m.