The appearance of crystal spots on aluminum materials is due to the segregation and segregation of alloy elements in aluminum alloys due to improper extrusion process and non-standard heat treatment, which leads to intergranular corrosion and ultimately precipitates white flocculent AL (OH) 3. After drying, crystal spots are formed. The component of aluminum alloy anodizing to form an oxide film is aluminum oxide. The film layer is dense and wear-resistant. Aluminum oxide is a zwitterionic substance that reacts with alkali to dissolve the film layer. The composition and content of different types of aluminum alloys are also different. The purity of aluminum directly affects the transparency of the oxide film, and the elements Si, Mn, Cr, and Mg in the alloy can affect the coloration of the oxide film.