The present disclosure discloses a method and device for reducing display brightness, and belongs to the technical field of display. Aspects of the disclosure provide a method for reducing display brightness. The method includes acquiring a first corresponding relationship between pixel values and voltages for reducing display brightness. The first corresponding relationship is determined based on a second corresponding relationship between pixel values and voltages and a ratio for brightness reduction. Further, the method includes determining a voltage corresponding to a pixel value of a pixel to be displayed based on the first corresponding relationship and at a scanning moment corresponding to the pixel, outputting the determined voltage to a data line corresponding to the pixel in a liquid crystal display screen.