The invention relates to a sliding device and a mounting structure thereof. The sliding device comprises a bracket and two chains, wherein the front portion of the bracket is provided with a front hinge structure, the left end and the right end of the rear portion of the bracket are both provided with first rear hinge structures and second rear hinge structures correspondingly, the first rear hinge structures are located in front of the second rear hinge structures, the two chains are connected to the left end and the right end of the rear portion of the bracket correspondingly, one chain ringon each chain sleeves a hinge shaft of the first rear hinge structure or the second rear hinge structure at the corresponding end, when the bracket is in the horizontal position under the pulling ofthe chains, the top plane of the middle of the bracket is the bearing working surface of the bracket, and the sliding device mounting structure is characterized in that the front part of the bracket is hinged to the lower part of the rear side of an electric cabinet through the front hinge structure, and one chain rings of the left chain and the right chain are installed at the left end and the right end of the upper part of the rear side of the electric cabinet correspondingly. According to the sliding device and the mounting structure thereof, a cover plate assembly of the electric cabinet can be easily moved, the working intensity of the maintenance personnel is relieved, and the safety is improved.