1. The local vasoconstrictive effect of hyperbaric oxygen and the increase of tissue oxygen partial pressure can help reduce tissue edema, lower intraosseous pressure, restore venous return and improve microcirculation; 2. Hyperbaric oxygen can increase the partial pressure of oxygen in the fracture area, especially in the bone scab and medullary cavity, which is conducive to enhancing the activity of osteoclasts and osteoblasts, proliferation of fibroblasts and accelerating the formation of bone scabs; 3. Hyperbaric oxygen can enhance the vitality of phagocytes, which is conducive to the absorption and removal of necrotic bone tissue; 4. Hyperbaric oxygen can enhance the resistance of local tissues to infection, especially anaerobic bacterial infection.