The invention discloses a novel mounting structure for a reactive power compensator, which comprises a compensator main body, fixing assemblies and a heat dissipation sheet, wherein the fixing assemblies are symmetrically mounted on two side surfaces of the compensator main body, and the compensator main body is fixed on the heat dissipation sheet through the fixing assemblies. When the compensator main body is mounted, a ventilation and heat dissipation surface of the compensator main body is abutted against the heat dissipation sheet through a heat dissipation assembly so as to arrange a wiring end of the compensator main body on the side surface, so that the detection is extremely convenient during wiring and after wiring, the heat dissipation effect is enhanced, and the safety is improved. The heat dissipation sheet is embedded in a heat insulation plate, and the heat dissipation sheet and the heat insulation plate are fixed in an electric cabinet box through bolts. When the compensator main body is mounted, it does not need to consider whether the existing holes in the electric cabinet box can meet the requirement of mounting the compensator main body or not, the heat dissipation sheet and the heat insulation plate are each to punch and can be conveniently matched with the existing holes in the electric cabinet box, and the influence of the heat dissipation sheet on the electric cabinet box is avoided.