As the medium with absorption and scattering properties,sea fog has strong attenuation effect on the laser. Combined with the physical characteristics of sea fog,the general calculating model of sea fog equivalent permittivity is derived according to the theory of dielectric polarization. Furthermore,the calculating model of attenuation rate is also obtained when laser is propagated through fog. As an example of experiential droplet spectrum of advection fog and droplet distribution of two sea fog cases,the attenuation model of equivalent permittivity is calculated and simulated,and the impact of sea fog physical characteristics on laser transmission effect is analyzed and evaluated. The results show that the impact of sea fog physical characteristics is incarnated in the model based on equivalent permittivity,which is obviously effected by sea fog characteristics such as visibility and droplet distribution.