The invention belongs to the field of technical facilities for laying power cables in cable trenches, and relates to a foldable cable support which is installed in a cable trench. The foldable cable support comprises a cable support body, and is characterized in that the cable support body is fixedly provided with connecting rods which are parallel to the wall of cable trench, each connecting rod is connected with the cable supporting rod perpendicular to the wall of the cable trench through a rotating shaft, a limiting block is arranged above the non-cantilever end of each cable supporting rod at one side of the rotating shaft, and the limiting blocks are fixed on the cable support body; and the surface, which is fixed with the wall of the cable trench, of the cable support body is provided with support fixing bolts. The foldable cable support is reasonable in structural design, the original fixed horizontal cable support is designed to be foldable, and the horizontal cable supporting rods can rotate upwards and be retracted until being perpendicular to the ground before cable laying or during cable troubleshooting, thereby expanding the activity space in the cable trench to be maximum extent, and providing convenience for movements of the maintenance personnel in the trench and entrance of maintenance equipment.