The present application discloses a method of fabricating an organic light emitting diode display substrate having a subpixel region and an inter-subpixel region. The method includes forming a pixel definition layer on the base substrate, the pixel definition layer being formed in the inter-subpixel region and defining the subpixel region of the organic light emitting diode display substrate; forming an insulating dielectric layer on a side of the pixel definition layer distal to the base substrate, the insulating dielectric layer being formed to define a first aperture region greater than the subpixel region; and, subsequent to forming the insulating dielectric layer, forming an organic light emitting layer in each subpixel region using a mask plate placed on the insulating dielectric layer.