Based on the painting perform ance of hot rolled steel plate in fram epainting production line, the perform ance of film pretreatm ent process and traditional phosphorization process com bined with “primer-topcoat in one” cathodic electrodeposition coating was com pared, and the effects on its corrosion resistance were researched. The results showed that the film pretreatment process could meet the technical requirem ents of “primer-topcoat in one” cathodic electrodeposition coating.