Combining the parameters of the radiation fog and the transmission fog at different visibility, the depolarization characteristics of the two clouds were studied. Discuss the reflection of different fogs and the degree of polarization of transmitted light as a function of transmission distance and visibility. Found by calculation that when the visibility of the cloud is constant, the increase of the transmission distance or the decrease of the visibility of the cloud when the transmission distance is constant will enhance the depolarization effect. And usually the cloud has a stronger depolarization effect on the reflected light than the transmitted light.