The invention provides a surface layer structure for a combined transformer shell. A door frame, an opening and a radiator shutter are arranged in the transformer shell; and a high pressure chamber door and a low pressure chamber door are arranged in the transformer shell; the surface layer structure is characterized in that by combining the positions of the door frame, the opening and the radiator shutter in the transformer shell, a painting layer in line with the installation environment pattern of the combined transformer is integrally distributed on the high pressure chamber door, the low pressure chamber door and the side wall of the shell; and a layer of protective varnish playing roles of sun shading, rain protection and corrosion prevention is covered on the painting layer. By adopting the surface layer structure and the surface layer processing method provided by the invention, the problem that the appearance of the original combined transformer is inharmonious with the surroundings is solved, patterns fused with the surrounding environment can be painted according to the actual situation no matter in what places, so that harmonious and attractive effects are reached; and moreover, through brushing varnish on the surface, sun shading, rainproof and corrosion-proof requirements of the painted pattern can be ensured, and the service life of the painted pattern is guaranteed.