Hyperbaric oxygen has been used for the treatment of traumatic brain injury due to various causes for more than 50 years, and foreign reports on hyperbaric oxygen therapy for neurosurgical diseases were published in 1967. Since the 1990s, a large number of clinical reports and studies have been published every year. Now there are more than 1000 articles published on hyperbaric oxygen therapy for severe craniocerebral injury and traumatic brain injury. One US article reported an improvement rate in the hyperbaric oxygen therapy group without the use of hyperbaric oxygen therapy. The traumatic brain injury referred to here includes severe cranial injury, cerebral contusion, diffuse axonal injury, subdural hematoma and epidural hematoma. The effectiveness of hyperbaric oxygen therapy for traumatic brain injury comes not only from case reports but, importantly, mainly from clinical observational studies and animal experiments and exploration of treatment mechanisms. When is the right time to start hyperbaric oxygen therapy in patients with traumatic brain injury? Generally speaking, the time to start hyperbaric oxygen therapy varies depending on the patient’s condition. After craniotomy, the patient’s vital signs are unstable, in short, the main indicators of life support such as temperature, pulse, respiration and blood pressure are not yet stable. Postoperative patients also have to go through pathological processes such as cerebral edema, cerebral hemorrhage, infection, and gastrointestinal bleeding. After the vital signs are stabilized and the condition is relatively stable, the patient will remain unconscious, with different degrees of hemiparesis, aphasia, choking and coughing, diplopia, and vision loss. At this point, hyperbaric oxygen therapy can be considered. What are the benefits of hyperbaric oxygen therapy? Studies have shown that the partial pressure of alveolar oxygen rises from 100 mmHg to 1400 mmHg at 2 atm. This is impossible to achieve at atmospheric pressure. Hyperbaric oxygen is not only an oxygen, it has a clear pharmacological effect, acting like a drug and acting in the pathophysiological processes of the body. The Ministry of Health has long administered hyperbaric oxygen as a drug. Hyperbaric oxygen not only significantly improves hypoxia in the body, but also has a restorative effect on nerve cells, reducing cell edema, nerve cell damage and collagen cell (supporting nerve cell survival) repair. There are numerous patients who have been cured by our department in the past 20 years. Some patients even “feel something new every day”. In 1996, 2001, and 2004, the Chinese Medical Association’s Hyperbaric Medicine Branch developed and revised indications and contraindications for hyperbaric oxygen therapy. It is important to select the indications and exclude the contraindications. Whether a patient can be treated with hyperbaric oxygen therapy should be weighed by the hyperbaric specialist according to his or her condition. If the vital signs are stable and contraindications to hyperbaric oxygen therapy are excluded, hyperbaric oxygen therapy should be given as soon as possible, the earlier the treatment, the better the efficacy and the less the sequelae.