To investigate whether hyperbaric oxygen therapy can improve the survival rate of fat transplantation and analyze the possible mechanisms. Ninety SD rats were randomly divided into 3 groups. All the rats were cut into pieces with about 5mL of fat from the abdominal cavity, rinsed with normal saline for 3 times, and cleaned with cotton pad adsorption method. Then, 3ml was removed, divided into 3 parts, and injected into three adjacent but not touching parts of the back. Group A received 1h/d hyperbaric oxygen therapy, group B received 2h/d hyperbaric oxygen therapy, and group C received no hyperbaric oxygen therapy. The hyperbaric oxygen therapy lasted for 10 consecutive days. Fat grafts from one site were randomly removed at 2, 4, and 6 weeks after surgery, respectively. ① the survival rate of fat transplantation in three groups was compared. ② observe the pathological section; ③ immunohistochemistry was used to detect and compare the expression of vascular endothelial growth factor. The survival rate of fat transplantation in group A was the highest. After subcutaneous transplantation of 1 ml of fat and 1 hour/day of continuous hyperbaric oxygen treatment for 10 days, the fat survival rates were 0.796 ± 0.071ml, 0.644 ± 0.151ml, and 0.473 ± 0.127ml at the second, fourth, and sixth weeks, respectively. The survival rate of fat transplantation in group B was the second. After subcutaneous transplantation of 1 ml of fat and 2 hour/day of continuous hyperbaric oxygen treatment for 10 days, the survival rate of fat was 0.624 ± 0.220ml, 0.494 ± 0.125ml, and 0.329 ± 0.153ml at the second, fourth, and sixth weeks, respectively. The survival rate of fat transplantation in group C was the lowest. After subcutaneous transplantation of 1 ml of fat and no hyperbaric oxygen treatment for 10 days, the fat survival rates were 0.461 ± 0.132ml, 0.290 ± 0.112ml and 0.169 ± 0.091ml at the second, fourth, and sixth weeks, respectively. We have made changes in the abstract of the article and marked in red color. Hyperbaric oxygen therapy is conducive to the survival of transplanted fat. Importantly, a short period of hyperbaric oxygen therapy (1h/d) can promote the survival of transplanted fat. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .