Photomask, manufacturing method thereof and method for manufacturing display device

The invention discloses a photomask, a manufacturing method thereof and a method for manufacturing a display device. The photomask comprises a substrate, a patterning light shielding layer, a flattening layer and an aligning structure, wherein the patterning light shielding layer is arranged on the surface of the substrate; the flattening layer and the patterning light shielding layer are positioned on the same surface of the substrate, and the flattening layer covers the patterning light shielding layer; the aligning structure is arranged on the surface far away from the substrate of the flattening layer; the photomask has a self-aligning function for light, is suitable for being applied to environments having high requirements on the alignment degree, so that an alignment light source isnot required during making of a polymer wall in a flexible display, the polymer wall is easier and more convenient to produce, the production equipment has high integration degree, and the productioncost of the polymer wall