An organic light emitting display panel and a display device are provided. The organic light emitting display panel includes a substrate, a plurality of organic light emitting diode elements in an array on one side of the substrate, a phase compensation film on a side of the organic light emitting diode elements away from the substrate, and a circular polarizer on a side of the phase compensation film away from the organic light emitting diode elements, wherein the phase compensation film compensates for phase retardation amounts of the circular polarizer at all viewing angles, so that a phase retardation amount of light obliquely passing through the circular polarizer and the phase compensation film is substantially consistent with that of light perpendicularly passing through the circular polarizer and the phase compensation film.