The invention belongs to the technical field of aramid fiber film preparation, and discloses self-cleaning aramid fiber film, a preparation method thereof, and applications thereof in gas separation. The method includes steps of: adding aramid fiber into a mixed solution of an organic solvent and a strong alkali, stirring to obtain a uniform solution, adding a pore-forming agent, stirring and degassing, casting on a substrate to form film, immersing the film together with the substrate into water, allowing the film to gel in water and be separated from the substrate so as to obtain gel film, drying the gel film to obtain aramid fiber film, dipping the prepared aramid fiber film into fluorine-containing epoxy resin dispersed by a solvent, taking the aramid fiber film out, and heating the aramid fiber film to obtain the self-cleaning aramid fiber film. A film casting liquid is prepared by dispersing the aramid fiber through the strong alkali, and then the aramid fiber film is prepared by a solution phase transfer method, thus maintaining the good molecular structure integrity of the aramid fiber, and preserving inherent performances of the aramid fiber, thus as high-temperature resistance, solvent tolerance and high strength. Then the fluorine-containing epoxy resin is grafted into the aramid fiber film to obtain the aramid fiber film with hydrophobicity or amphiphobicity, thus obtaining the self-cleaning aramid fiber film.