A display control method and a device for an N primary color display screen and a display device are provided in the embodiment of the present disclosure, and belong to the field of display technology. The N primary color display screen comprises a plurality of pixel units, each pixel unit of the plurality of pixel units comprising N primary color sub-pixels, N being an integer equal to or greater than four. The display control method comprises: acquiring an M primary color input signal of each pixel of an original image, which comprises a plurality of pixels corresponding to the plurality of pixel units respectively, each pixel of the plurality of pixels displaying a color image with M primary colors, M being an integer greater than one and less than N; calculating, according to the color coordinate of each primary color of the N primary color display screen and the M primary color input signal, an N primary color input signal of the pixel units corresponding to the N primary color display screen. The technical solution of the examples of the present disclosure can obtain a four primary color input signal, a five primary color input signal and even a six primary color input signal on the basis of a three primary color input signal.