The invention discloses an aluminum section bar surface brightening method. The aluminum section bar surface brightening method comprises the steps of sand blasting, oil removing, water washing, polishing, oxidizing, coloring, medium-temperature hole sealing and electrophoresis curing, wherein the polishing is performed inside a three-acid polishing tank, the three-acid polishing tank contains theingredients of, in percentage by weight, 65-85% of phosphoric acid, 14-22% of sulfuric acid and 6-8% of nitric acid, the polishing is performed for 20-25 min under the condition of the polishing temperature being 100-110 DEG C, and by means of reduction of the oxidizing temperature and the oxidizing tank sulfuric acid concentration, the oxide film production speed can be reduced, a more uniform and compact oxide film is obtained, and appearance of flow marks in aluminum materials is reduced; and the aluminum materials are not prone to fading when being subjected to the water washing and electrophoresis after being subjected to the coloring and the hole sealing and high adhesion can be obtained when the electrophoresis is performed in a half hole sealing state, and when combination with the electrophoresis is performed, suitable voltage can slow down the paint film coating speed, in addition of an appropriate curing method, dye color changing and coating surface roughness and excessivebrittleness can be prevented, and the coating adhesion is improved.