Based on the basic theory of vector radiative transfer equation, considering the influence of different kinds of cloud layers and different concentrations of advection fog, we developed a simplified two-layer atmosphere structure to a three-layer one and applied an adding-doubling method to simulate the scattering process of skylights through multilayer atmosphere. Furthermore, with the Rayleigh and Mie theory, the distribution characteristics for atmosphere, cloud, and fog layers were described, respectively, and the adding-doubling method was utilized to build the polarization distribution model of skylights under different typical marine environments. In addition, we investigated the relationship between the degree of polarization (DOP) and the observed altitude angle on the meridian of the sun. The results show that the skylight DOP varied regularly with the observed altitude angle. Moreover, with the rise in the optical thickness and with the increase of the cloud size and advection fog particles, DOP gradually increased. In conclusion, this study provides theoretical references for the selection of weather conditions and observation locations in the vertical polarization detection under complicated marine environments.