Abstract： Objective:To investigate the effects of hyperbaric air saturation exposure on lung oxidative injury and inflammatory cytokines in rats.Methods:A total of 30 male SD rats were randomly divided into three groups：experimental A group，experimental B group，and control group（ n=10 per group）. The experimental A group and the experimental B group were pressurized with air to 50 m and exposed to saturation for 24 h，and the decompression time was 59.55 h in total. The control group was placed in a hyperbaric cabin to simulate all experimental processes except being pressurized and decompressed. The behavioral performance of the rats in experimental B group was observed for 2 hours after leaving the cabin. Meanwhile，the behavioral performance of the rats in the experimental A group and the control group was observed for 5 minutes after leaving the cabin，and lung tissue samples were immediately collected to detect the lung wet/dry weight ratio of the rats. The levels of malondialdehyde（MDA）and hydrogen peroxide（H 2O 2），the activities of manganese superoxide dismutase（Mn-SOD）and catalase（CAT），and the levels of interleukin-1β（IL-1β）and tumor necrosis factor-α（TNF-α）were measured by the enzyme-linked immunosorbent assay（ELISA）in the experimental A group and the control group. Results:The behavioral performance of rats in the three groups was basically normal，with normal walking and breathing. There was no significant difference in the lung wet/dry weight ratio of the rats between the experimental A group and the control group. The levels of MDA，H 2O 2，IL-1β，and TNF-α in lung tissue of the rats in the experimental A group were significantly increased，while the activities of Mn-SOD and CAT in lung tissue of the rats in the experimental A group were significantly decreased，and the difference was statistically significant compared with the control group（ P<0.01）. Conclusion:Saturation exposure to hyperbaric air can cause oxidative injury and changes of inflammatory cytokines in lung tissue of rats，which may be related to prolonged exposure to hyperbaric air.