The invention relates to a cable laying structure of a 500kV underground substation. The structure comprises a plurality of cable laying racks and a cable, wherein the cable is arranged on the cable laying racks, each cable laying rack comprises a vertical post and a plurality of horizontal rods, the vertical post is vertically arranged, the plurality of horizontal rods are perpendicular to the vertical post and are parallel to one another, one end of each horizontal rod is hinged with the vertical post via a pin shaft so that the horizontal rod can be rotated to a vertical direction from a horizontal direction in a plane of the cable laying racks. Compared with the prior art, the cable laying structure has the advantages of space saving, wear resistance and the like and is easy to replace.