The paper shredder has two main components, "paper cutter" and "electric motor", which are closely connected by belts and gears. The motor drives belts and gears to transfer energy to the paper cutter, and the paper is cut The knife is rotated to shred the paper with a sharp metal corner. Some paper shredders on the market can choose two or more shredding methods. Different shredding methods are suitable for different occasions. If it is a general office occasion, choose the segment, granular, filament, or strip shape. But if it is used in some occasions that require high confidentiality, it must be foamed. At present, the paper shredding method composed of four knives is the most advanced working method. The paper shredding is neat and tidy, which can achieve the effect of confidentiality. The cutting principle of the paper shredder is that the blades or cutters are arranged in a dislocation, and the paper is torn apart under the action of the power source. If the knife or blade is provided with a tip, the effect of shredding paper is segmental or granular, and if the knife or blade is provided with no tip, the effect is strip-shaped.