Provided are a display substrate and a manufacturing method therefor, and a display device. The display substrate includes: a base substrate, a pixel defining layer (40, 40′) formed on the base substrate, and a light emitting layer located in a sub-pixel region (P) defined by the pixel defining layer (40, 40′), wherein, the pixel defining layer (40, 40′) includes: a reflecting layer (41, 41′), configured such that light emitted from the light emitting layer to the reflective layer (41, 41′) is reflected to a light outgoing side of the display substrate. The display device adopting the display substrate not only can effectively solve the problems of light leakage and light color interference, but also can effectively improve light out-coupling efficiency and color purity.