The invention discloses a power transformer tank waste heat utilization device which comprises a quadrilateral transformer tank. A hollow structure is arranged in the middle of the transformer tank, peripheral side walls of the transformer tank have a certain thickness, connecting pipe holes are formed in the peripheral side walls of the transformer tank, connecting pipes are arranged inside the connecting pipe holes, flow guide channels are formed inside the transformer tank by the connecting pipes, water inlet ends of the connecting pipes are connected with water inlet pipes, water outlet ends of the connecting pipes are connected with water outlet pipes, heat insulation layers are arranged on the peripheries of the water inlet pipes and the water outlet pipes, the connecting pipe holes are of U-shaped structures, a plurality of U-shaped structure connecting pipe holes are uniformly formed in the side walls of the transformer tank, and every two U-shaped structure connecting pipe holes are connected together through one connecting pipe. Unused waste heat can be reused, energy is saved, and environments are protected.