The methods of reducing waste water and waste liquid include reasonable control of water control time and control of charging angle to reduce the amount of tank liquid carry-out, and try to use two-level and three-level countercurrent rinsing to reduce water consumption. The washing water after acid etching and degreasing is used for washing after alkaline corrosion, and the washing water after oxidation is used for washing after acid etching and degreasing. In addition, in order to reduce or avoid the discharge of waste water and waste tank liquid, the production line should design and use various recovery devices, such as acid etching recovery device, alkaline etching recovery device, anodizing aluminum removal device, coloring liquid RO recovery device, electrophoretic paint RO Recovery devices. The use of these recovery devices can reduce the amount of waste water and waste liquid discharge to a large extent, and also greatly reduce the production cost.