The present disclosure relates to an OLED panel, manufacturing method thereof, and a display device. The method for manufacturing an OLED panel comprises: forming an auxiliary electrode layer on a substrate, and forming a morphological transformation layer on the auxiliary electrode layer; forming an organic functional layer, wherein the organic functional layer covers the morphological transformation layer; removing the morphological transformation layer and a part of the organic functional layer corresponding to the morphological transformation layer from the auxiliary electrode layer; and forming a cathode layer on the organic functional layer and the auxiliary electrode layer.