The multiple scattering propagation model with Monte Carlo method is established, and characteristics in non-line-of-sight (NLOS) atmospheric scattering optical communication channel in fog weather are simulated and analyzed by using the model. The absorption loss for visible light or infrared light is relatively low in atmosphere, and the Rayleigh scattering effect generated when visible light or infrared light barges up against air molecules can be ignored. At the same time, there will be a strong Mie scattering effect that occurs between the signal photon in visible light or infrared light wave band and fogdrop particles, so the visible light or infrared light is generally used in long distance scattering optical communication systems. The wavelength selected in simulation is 620 nm, and the relationship between transmission loss and visibility is analyzed in different communication distances in fog weather. The results demonstrate that there will be a visibility that can makes transmission loss lower when the communication range, the elevation angle, the transmitting beam-width divergence and the field-of-view are determined.