Provided are an OLED array substrate and a manufacturing method thereof, and a display device. The OLED array substrate includes a substrate and a plurality of pixel units provided thereon. The plurality of pixel units are arranged into a plurality of rows extending in a first direction and a plurality of columns extending in a second direction. Each pixel unit includes a plurality of subpixels emitting light of different colors. At least two subpixels emitting light of the same color are adjacent to each other in at least one of the first direction and the second direction.