The embodiments of the present disclosure disclose a collimated light source, a manufacturing method thereof and a display device. The collimated light source includes a substrate, a film layer with a plurality of concave microstructures on the substrate, a reflective layer on the film layer, and a plurality of light-emitting parts corresponding to the concave microstructures one-to-one. Each of the light-emitting parts is located at a focal point of a corresponding concave microstructure. According to the embodiments of the present disclosure, the light emitted from each light-emitting part is reflected by the reflective layer on the corresponding concave microstructure and then exits in parallel light from a side of the reflective layer facing away from the substrate.