An OLED display element, its manufacturing method and a display device are provided. The OLED display element includes a light-emitting pixel unit. The light-emitting unit includes an anode arranged above a base substrate, a cathode arranged opposite to the anode, and a micro cavity formed between the anode and the cathode. The micro cavity includes an organic light-emitting layer, and the anode includes an ITO layer arranged opposite to the cathode and a metal oxide conductor layer arranged at a side of the ITO layer that is farther away from the cathode than the other side of the ITO layer.