In response to the suggestion that more hyperbaric oxygen treatment would produce serious side effects and adverse reactions, our department conducted a retrospective analysis of patients with a long course of treatment, in which the case with the most number of treatments was reported as follows: Case: Li XX, male 62 years old, case number 14237, worker, Changsha Railway Nail Factory, head and body trauma in December 2004, head and abdominal surgery in 161 hospital, December He was transferred to our hospital on December 20. Physical examination: coma, stimulation of the left limb showed activity. There was no contraction of the right limb when stimulated. On January 8, 2005, the patient was treated with hyperbaric oxygen therapy (the single dose of hyperbaric oxygen was 2.2 ATA at a steady pressure for 80 minutes each time, and the total treatment time in the chamber was 100 minutes, usually twice a day in the acute period and once a day in the recovery period). In August 2007, the patient had 200 hyperbaric oxygen treatments and was able to speak and communicate with others, but he could not speak clearly and could answer questions correctly. On January 20, 2010, he had 280 hyperbaric oxygen treatments, and was clear, responsive to speech and unclear. Now he is clear, his mental status is acceptable, his language is responsive and humorous, but his speech is not clear, he can walk independently, but his gait is stiff and unsteady, his muscle strength of right lower limb is grade 4, left lower limb is grade 5, muscle tone of both lower limbs is high, and muscle tone of both upper limbs is normal. From October 26, 2009 to December 30, 2013, a total of 770 hyperbaric oxygen sessions were performed, with slight improvement in intelligence, speech, and physical activity, without any toxic side effects or adverse reactions. There were no significant changes in the magnetic resonance ventricle. Discussion: The patient’s brain tissue was obviously repaired after hyperbaric oxygen therapy after traumatic brain injury surgery, and her mental ability was restored from coma to wakefulness. The muscle strength of the right leaning limb gradually recovered from grade 0 to grade 4, and could walk with assistance, but the muscle tone was still high, and MRI showed obvious brain atrophy. The severity and occurrence of brain atrophy after traumatic brain injury is completely related to the severity of the traumatic brain injury, and the brain atrophy will gradually progress, and the speed of its progress is related to the amount of preserved brain nerve function, and the less preserved brain nerve function the more rapidly the brain atrophy progresses. Hyperbaric oxygen therapy can slow down the progression of cerebral atrophy. In this case, the patient underwent hyperbaric oxygen therapy 770 times for nearly 5 years from March 2009 to December 2013, but there was still some improvement in cerebral neurological function, and there was no significant change in the brain MRI ventricle. In 2007, we told the family that we could not do hyperbaric oxygen, but the family said, “I know whether to do it or not, because I am always with him. After 2009, although the symptoms did not improve significantly, if we do not do hyperbaric oxygen, the mental status, language and physical activity will deteriorate, and if we do hyperbaric oxygen, we can maintain the current situation”. This patient had a total of 1077 hyperbaric oxygen treatments from January 2005 to the present (May 16, 2014) without any adverse effects or toxic side effects. Conclusion: This patient with heavy cranial injury is currently the longest patient in our department for hyperbaric oxygen therapy, and no adverse reactions and toxic side effects were found in this patient with a long course of hyperbaric oxygen therapy. It also suggests that it has a facilitating effect on the recovery of brain function and a slowing effect on the progressive brain atrophy caused by brain injury.