In the present study, Al2O3 (insulator), ZrO2 (ionic conductor) and (ZnO semiconductor) coatings were prepared by cathode plasma electrolytic deposition (CPED) method on stainless steel substrates. The surface morphologies and cross sections of the coatings were analyzed. The contributions to the electric current densities during the CPED process were studied. A double dielectric layers model was proposed to systematically study the effect of the electrical conductivities on the coating structures. The results showed that the coating structures and the electrical breakdown mechanism were closely related with the electrical conductivities of the coatings and the gas film. The different structures of the coatings can be attributed to the electric conductivity difference between the coatings and the gas film.