Provided are an organic light-emitting diode display panel and a manufacturing method thereof, and a display device, in the field of display technology. The OLED display panel includes: a base substrate and plurality of light-emitting units. Each light-emitting unit includes a first electrode, a second electrode, and a light-emitting layer between the first electrode and the second electrode, and a ratio of areas of light-emitting layers in the plurality of light-emitting units is within a threshold range.