The present disclosure provides a method and an apparatus for adjusting luminance of a display device. The method of adjusting luminance of the display device includes: determining a gray scale level interval on a target gray scale curve based on a maximum luminance value and a minimum luminance value to be set; determining a target luminance value for each grayscale level of the display device on the target gray scale curve according to the gray scale level interval; and adjusting luminance of the grayscale level of the display device based on the determined target luminance value.