The invention discloses a power tunnel cable support. The power tunnel cable support comprises a fixed plate, an arc cable support body, support rods and backstop rods, wherein a tangential direction of a middle point of the cable support body is vertically arranged, one end of the cable support body is fixedly connected with one end of the fixed plate, a plurality of threaded holes are horizontally formed in an arc camber surface of the cable support body, one end of each support rod is fixedly connected with threaded rods matched with the threaded hole, the other ends of the support rods are rotatably connected with the backstop rods, the threaded rods are arranged in the threaded holes, the lower surface of the fixed plate is inwards sunken to form a groove, a support leg is connected to the groove and can rotate by taking an axial line as a shaft, the axial line is arranged on the same horizontal plane with the lower surface of the support leg and is perpendicular to the length direction of the support leg, a bolt is further arranged on the fixed plate, and the support leg can be fixed on the fixed plate by adjusting the bolt. By the power tunnel cable rack, the problems that the support is poor in stability, a power transmission cable is easy to be separated from the support, and the end part of a cross rod of the support is sharp and directly faces the middle of a power tunnel to easily cause a construction worker to be hurt in the prior art are solved.