Abstract： Objective:To investigate the effects of hyperbaric oxygen（HBO）therapy at different times on the curative effect，cerebral blood flow，and pituitary function of patients with traumatic brain injury（TBI）.Methods:A total of 88 TBI patients who were treated in the General Hospital of Taiyuan Iron & Steel（Group）Co.，Ltd. from October 2019 to October 2020 were selected and divided into early group（ n=45）and late group（ n=43）according to the timing of HBO treatment. Both groups were given HBO on the basis of conventional treatment，the early group was given HBO within 1 month after trauma；while the late group was given HBO within 1–2 months after trauma. The clinical efficacy，cerebral blood flow，and the scores of Glasgow Coma Scale（GCS），Activities of Daily Living（ADL），Disability Rating Scale（DRS），and Glasgow Outcome Scale（GOS）were compared between the two groups. The changes of serum-related pituitary hormone levels before and after treatment were determined by using chemiluminescence immunoassay. Results:The total clinical effective rate（77.8%）in the early group after treatment was higher than that in the late group（44.2%），and the difference was statistically significant（ P<0.05）. Compared with those before treatment，the scores of GCS，ADL，and DRS in the two groups were significantly improved after treatment；the scores of GCS and ADL in the early group were significantly higher than those in the late group，and the DRS score was significantly lower than that in the late group，and the differences were statistically significant（ P<0.01）. After treatment，the GOS grading of patients in the early group was better than that in the late group，and the difference was statistically significant（ P<0.05）. There was no significant difference in cerebral blood flow between the two groups after treatment（ P>0.05）. There was no significant difference in the levels of adrenocorticotropic hormone（ACTH），growth hormone（GH），thyroid stimulating hormone（TSH），prolactin（PRL），follicle-stimulating hormone（FSH），and luteinizing hormone（LH）between the two groups before treatment（ P>0.05）. Compared with those before treatment，the level of GH in the early group was significantly decreased after treatment；the level of LH in the late group was significantly increased after treatment，and the differences were statistically significant（ P<0.05）. After treatment，the level of FSH in the early group was significantly lower than that in the late group，and the difference was statistically significant（ P<0.05）. Conclusion:Early HBO treatment in patients with TBI can effectively improve brain tissue hypoxia，which is beneficial to the recovery of neurological function.