1. A pixel array structure of a display device comprising a plurality of pixel units, wherein each of the pixel units comprises four color pixels and a white sub-pixel, wherein the four color pixels do not overlap each other, wherein each of the four color pixels does not comprise a white sub-pixel, and comprises a plurality of color sub-pixels, and one of the plurality of color sub-pixels is a smallest color sub-pixel, wherein the white sub-pixel is surrounded by the four smallest color sub-pixels of the four color pixels and immediately neighbors each of the four smallest color sub-pixels, wherein the four smallest color sub-pixels of the four color pixels are of the same color.