An adjustment method, which is adapted in a display including a plurality of pixels and a plurality of backlight illuminants, includes: inputting an image signal with a single chromaticity and luminance to the display; adjusting a set of a backlight red gray-level luminance, a backlight green gray-level luminance, and a backlight blue gray-level luminance for each of the illuminants, and the difference of the luminance of the backlight illuminants is between 0 and 10%; and adjusting a set of a pixel red gray-level value, a pixel green gray-level value, and a pixel blue gray-level value for each of the pixels, and the difference of the luminance of the pixels is between 0% and 5%.