The invention relates to a device for reducing a driving voltage of a blue phase liquid crystal display, and belongs to the technical field of liquid crystal displays. The device comprises an upper polaroid, an upper substrate, a protecting film, a color filter film, a blue phase liquid crystal, N Pixel electrodes, N Common electrodes, 2N bulges, an insulating layer, a lower substrate and a lower polaroid, wherein one surface of each bulge is connected with the lower surface of the color filter film or the upper surface of the insulating layer, and the rest part of each bulge is positioned in the Pixel electrodes or the Common electrodes; and the Pixel electrodes and the Common electrodes are alternately distributed at intervals, or the Pixel electrodes and the Pixel electrodes are distributed at intervals, or the Common electrodes and the Common electrodes are distributed at intervals. By introducing the bulge structure, the device effectively increases the transverse effective electric field in the region of the blue phase liquid crystal so as to greatly reduce the driving voltage of the blue phase liquid crystal display. Because the longitudinal sections of the electrodes have gradients, the device improves the light transmission rate, can utilize the conventional production equipment and conditions of the enterprise, saves energy and promotes the research and development and the mass production of the next generation liquid crystal display.