The present invention relates to the field of display, and discloses an organic light emitting diode array substrate, a manufacturing method thereof, and a display device, for the purposes of enlarging the color gamut of a display device and improving display quality. The organic light emitting diode array substrate comprises a substrate and multiple micro-cavity organic light emitting diodes which are disposed on the substrate and are arranged in arrays; wherein an angle exists between a light emitting surface of at least one micro-cavity organic light emitting diode and the plane of the substrate. In the embodiments of the invention, an angle exists between a light emitting surface of at least one micro-cavity organic light emitting diode and the plane of the substrate, such that the light with shorter wavelengths in the spectrum of the micro-cavity organic light emitting diode can be emitted in the direction of direct vision. The color coordinate value of a pixel can thus be changed, the pixel color is deepened, the color gamut of the display device is enlarged, the display color is more gorgeous, and the display quality is greatly improved.