There exist various of fog drop size distributions in advection fog and radiation fog, which result in the different attenuation performances as light propagates in fog field. Mie theory can describe the scattering and attenuation of aerosol particles in fog field, while light propagation follows the principle of dynamic particles conservation. In this paper, fog drop size distribution is applied to modify the scattering phase matrix of aerosol particles, and the scattered light′ s polarization can be solved when infrared light penetrates into aerosol particle clusters. The results show that aerosol particles′ depolarization mainly depends on fog drop size distribution, fog drop refractive index, absorption coefficient and incident wavelength. In the forward-scattering area, depolarization decreases as visibility increases, while the opposite trend occurs in most backwardscattering area.