The invention discloses a highway crossing support frame for power grid construction. One side of the upper part of a frame is provided with a flat plate. A bottom plate is arranged on the upper partof the flat plate. One side of the bottom plate is provided with a coaming plate. First support rods are movably installed at the two ends of the coaming plate through hinges. One end of a second hydraulic cylinder is movably connected with a connecting rod, and the other end of the second hydraulic cylinder is movably connected with the first support rods through a hinge head. A second support rod is movably connected with a first connecting plate. One end of a third hydraulic cylinder is movably connected with the first support rods through the hinge head, and the other end of the third hydraulic cylinder is movably connected with the second support rod through the hinge head. The first support frame and the second support frame are arranged on the vehicle body. The second hydraulic cylinder is utilized to support the first support frame and the third hydraulic cylinder is utilized to support the second support frame in use so that the erection of the support frame is quickly and efficiently completed, the efficiency of cable construction is improved, the stability of the support frame is enhanced and the personal safety of construction personnel and highway colleagues is guaranteed.