Abstract: Based on the fog drop size distribution (DSD) model of radiation and advection fog, the propagation attenuation of the fog is obtained in THz band by using Rayleigh absorption approximation and Mie theory. The results show that the fog attenuation in THz band is larger than that in microwave and millimeter band. The attenuation is increases as the water content increases or as the visibility decreases. The attenuation of fog with same water content or visibility varies non-monotonically with frequency increases. Meanwhile, the effect of temperature is not significant during the range fog can presence and has no regular pattern in the THz band.