General oxygen inhalation is the inhalation of oxygen at atmospheric pressure to treat a disease, which can also be called normobaric oxygen therapy. Hyperbaric oxygen is a gas therapy that allows the patient to inhale oxygen at a certain level of partial pressure of oxygen above one atmosphere. Often, when patients learn from books or the Internet that hyperbaric oxygen is good for the disease and ask for hyperbaric oxygen, some doctors are afraid of trouble and say to the patient: “There is oxygen in the ward, it is the same to inhale more time in the ward”. This is a wrong concept. Hyperbaric oxygen and atmospheric oxygen not only have quantitative differences, but more importantly, qualitative differences, the differences are: 1, hyperbaric oxygen can increase the physical dissolved oxygen in blood and tissues, to achieve bloodless life, that is, to remove the red blood cells in the animal’s body, under hyperbaric oxygen, the animal’s life is smooth, but atmospheric oxygen can not do this. 2.Hyperbaric oxygen can increase the penetration of oxygen, and thus can treat the local tissue cell hypoxia due to vascular obstruction, vascular spasm, or cell edema. 3, hyperbaric oxygen can increase the reserve of oxygen in tissues, which can make the body’s tolerance to hypoxia improve, so that the body can pass the dangerous period to win time, hyperbaric oxygen can do cardiac surgery under no extracorporeal circulation. 4, hyperbaric oxygen can kill anaerobic bacteria, gas gangrene has a very good therapeutic effect. 5.Hyperbaric oxygen can compress the imprisoned gas in the body, which has unique effect on the treatment of air bubble obstruction of respiratory tract in irritating toxic gas poisoning, treatment of decompression sickness, intestinal flatulence and intestinal pneumocystosis. Since atmospheric oxygen is unable to do the above points or ineffective, while hyperbaric oxygen has the above direct effects, thus producing regulatory effects on various systems of the body, such as mildly raising blood pressure, promoting endocrine and glucose utilization, enhancing liver and kidney functions, regulating cell cycle and enhancing chemotherapy and radiotherapy effects of cancer, etc. These effects are not available with atmospheric oxygen. Atmospheric oxygen has only one effect like hyperbaric oxygen, which is to increase the oxygen saturation of blood. The effect of normobaric oxygen therapy can only be seen when the patient is in respiratory distress due to cardiac, pulmonary or central nervous system causes, resulting in abnormal oxygen saturation. It can be said that as long as the oxygen saturation is normal there is no need for normobaric oxygen therapy, but there are many diseases with normal oxygen saturation that must be treated with hyperbaric oxygen therapy.