The present disclosure provides an organic light-emitting diode display substrate, a method of preparing the same, and a display device. The organic light-emitting diode display substrate includes: a light-emitting layer, a light modulation layer, and a color conversion layer, in which the light-emitting layer is configured to emit first color light, the light modulation layer and the color conversion layer are arranged on different light-exiting paths of the light-emitting layer, the color conversion layer is configured to convert first color light into second color light and third color light, and the light modulation layer is configured to modulate an emergent direction of first color light.