An optical film, a color filter substrate, manufacturing methods thereof and display devices are provided, in the field of liquid crystal display technology. The color filter substrate includes a base, a color resistant layer and a diffusion layer. The color resistant layer and the diffusion layer are arranged on the base, and the color resistant layer and the base are arranged at the same side of the diffusion layer. The color resistant layer comprises a plurality of color resistant blocks which are arranged in an array. The diffusion layer comprises a plurality of diffusion structures which are arranged to be in one-to-one correspondence to the plurality of color resistant blocks. Each of the plurality of diffusion structures is configured to diffuse light vertically emitted from the color filter substrate.