A photolithography method, a method of preparing a flexible substrate and a photoresist drying device are provided. The photolithography method includes: providing a base substrate on which a material layer to be etched is formed, in which the base substrate includes an intermediate region and a peripheral region surrounding the intermediate region; coating a layer of photoresist on the base substrate, in which the photoresist is coated in the intermediate region and the peripheral region, and is formed to cover the material layer to be etched; and drying the photoresist and simultaneously performing a first exposure process on the photoresist coated in the peripheral region.