The present disclosure relates to a method of manufacturing an OLED display panel, a display panel and a display device. A method of manufacturing an OLED display panel, comprising: providing a backplane, wherein a light-emitting layer is provided on the backplane, and an encapsulation layer is provided on the light-emitting layer; forming an organic layer on a side of the encapsulation layer away from the light-emitting layer using an organic material; patterning the organic layer to form a first region covered by the organic layer and a second region not covered by the organic layer on the encapsulation layer; etching the organic layer in the first region to form a plurality of pits on a surface of the organic layer away from the encapsulation layer; filling the plurality of pits with a metal to form a black mask layer; forming a color film layer in the second region; and forming a planar layer covering the color film layer and the black mask layer.