In a broad sense, if the oxygen partial pressure is higher than the oxygen partial pressure at atmospheric pressure (21kPa), they can be called high partial pressure oxygen or hyperoxia. Hyperoxia is often used in diving operations, underwater special operations and clinic treatment. When in diving operations. Hyperoxia can shorten the decompression time after diving and avoid decompression sickness. In underwater special operations, a fully closed breathing apparatus is used to breathe high partial pressure. Oxygen can also improve its concealment. Hyperoxia can also improve the function of ischemic and hypoxic tissues in clinic treatment. However, if the oxygen pressure exceeds a certain threshold, or the breathing oxygen exceeds a certain time, it will cause adverse effects on the body, that is, oxygen toxicity. Currently, oxygen toxicity is a major factor that limited oxygen use in diving operations, underwater special operations, and clinical treatment. Oxygen toxicity is divided into lung type, brain type and eye type. When the oxygen partial pressure is between at 60 ~ 200 kPa, the damage to the body is mainly manifested in the lungs. It is called pulmonary oxygen toxicity. When the oxygen partial pressure exceeds 300 kpa, the damage caused by oxygen toxicity is mainly manifested in the central nervous system, which is called central nervous system oxygen toxicity or brain-type oxygen toxicity.