The invention discloses a support frame for a transmission line of an electric power system, which includes an arm frame, the arm frame is a U-shaped groove, the arm frame is fixed on the wall, bolt holes are arranged on both sides of the arm frame, and the support seat is fixed by fixing bolts On the arm frame, the support seat is a triangle; the lower end of the support seat is a rib of the triangle, and the upper end is a surface; the upper end surface of the support seat is provided with an arc-shaped wire groove guide rail, and the wire groove guide rail is provided with a wire groove. The length of the trunking is 0.5-1m, and the trunking is made of plastic. When in use, the ledge is installed on the wall, the cable can be laid after the supporting frame is installed, and the cable can be placed in the wire groove after the cable is laid. The support length is increased, and the use of the support frame of the present invention can prevent the cable from bending without increasing the installation support point, which solves the problem of cable bending caused by point support when the cable is laid in the tunnel, and the increase in the use length wastes the cable. If support points are added, it will be time-consuming and labor-intensive.