The invention relates to a polyvinyl chloride (PVC) special box cover for inner thermal insulation walls and an application construction method thereof. The PVC box cover is a square box without the bottom and is matched with a junction box in size. Two round holes for lead wires to penetrate are respectively arranged in the middle of the right lateral wall and the left lateral wall of the PVC box cover, and the outer edges of the right lateral wall and the left lateral wall of the PVC box cover are respectively connected with screw hole bases for connecting a switch panel. The PVC special box cover for the inner thermal insulation walls and the application construction method of the PVC special box cover solve the problem that the junction box and the panel cannot be installed because of the thermal insulation thickness of the walls and the increased depth of the junction box, and the installed panel is on the same level with the wall surface and is attractive and firm.