And luminance adjustment method of a display device

The invention discloses a display device and a brightness adjusting method thereof. The display device comprises a plurality of pixel units. Each pixel unit comprises red sub-pixels, green sub-pixels, blue sub-pixels, and white sub-pixels. The method comprises the steps of acquiring a standard gamma curve for adjusting the brightness of the display device, wherein the gamma value of the standard gamma curve is gamma 0; acquiring a green gamma curve corresponding to the green sub-pixels, wherein the gamma value of the green gamma curve is gamma G; adjusting the green gamma curve to be offset from the standard gamma curve so as to improve the gray-scale brightness of the green sub-pixels, wherein gamma G is smaller than gamma 0. The color gamut of the display device is 77% or more of the NTSC color gamut. According to the technical scheme of the invention, the problem that color pictures displayed by the display device of the RGBW pixel structure are low in brightness can be solved.