On the basis of Mie scattering theory, the effect of fog with different concentration on the polarization characteristics of a surface ship target is analyzed in a simulation experiment. By carrying out numerical simulation with a 6SV model, the data about the effect of fog on target polarization characteristics is obtained. It is found that with the increase of fog concentration, the depolarization phenomenon is getting more obvious. The reason of this depolarization phenomenon is analyzed. The result is of reference value to the application of polarization detection technologies in fog environment.