Facing the increasing number of obese people, besides having a reasonable diet, fitness, surgical liposuction is also an excellent choice for them. In recent years, new techniques such as resonance liposuction, ultrasound liposuction and laser liposuction have been developed, but as the most classic negative pressure liposuction, this technique is still the first choice of most plastic surgeons. When performing liposuction, the surgeon will inject fluid into the body, what does it do? The swelling fluid causes the fat cells to gradually separate apart, thus liquefying the fat tissue for the suction operation. In traditional negative pressure liposuction, the first step is to measure and draw a line to mark the area and amount of liposuction, make a number of small openings of 3 to 5 mm in hidden areas (mainly to prevent the formation of wound scars affecting the aesthetics), inject the swelling fluid, wait for the fat tissue to soften and separate, then pump the liposuction needle’s back and forth and use the negative pressure to extract the fat out. The main advantages of swelling fluid: 1. reduce intraoperative bleeding; 2. reduce the amount of general anesthetic drugs including postoperative anesthetics; 3. facilitate the suction movement of the liposuction needle in the tissue; 4. the suctioned fat cells are more complete and can be used for autologous fat transplantation; 5. reduce the amount of intravenous rehydration fluid.