As is known to all, anodic oxide film is composed of a perpendicular to the metal surface of hexagonal crystal cell, every cell center have a film hole, and with a strong adsorption capacity, when the oxidation of aluminum in the dye solution, dye molecules by diffusion into the film hole of oxide film, at the same time and the oxide film formation is difficult to separate ionic bond and covalent bonds. This bond is reversible, desorption will happen under certain conditions. After dyeing, therefore, must pass a hole sealing process, the dye fixation in film hole, with increase of the oxide film properties, such as corrosion resistance, abrasion resistance.