The invention provides a waterproof opposite-edge aluminum alloy lifting mold and a method for constructing waterproof opposite edges by using the waterproof opposite-edge aluminum alloy lifting mold.The aluminum alloy lifting mold is suspended above a roof aluminum template through a supporting rod piece, the aluminum alloy lifting mold includes lifting mold beams and lifting mold aluminum templates arranged on both sides of the lifting mold beams, the supporting rod piece includes a screw rod, a lifting mold beam fixing assembly is arranged on the upper part of the screw rod, a roof aluminum template fixing assembly is arranged on the lower part of the screw rod, the lifting beam fixing assembly includes top nuts and detachable supporting plates arranged on the lower parts of the top nuts, the detachable supporting plates are arranged in the length directions of the waterproof opposite edges, the lifting mold beams are arranged on the detachable supporting plates and the two sides of the screw rod, and the lifting mold beams are fixed to the detachable supporting plates through pin bolt and pin piece assemblies; and the roof aluminum template fixing assembly includes a footing piece and a bottom nut which is arranged on the screw rod and used for clamping and fixing the roof aluminum template. According to the waterproof opposite-edge aluminum alloy lifting mold, installation and fixation are convenient, the general rate is high, the waterproof opposite edges can be poured with structural roof concrete, simultaneous pouring and construction are achieved, no constructionjoint among the waterproof opposite edges and the structural plate surface can be ensured, and the self-waterproof effect of the structure is enhanced.