Abstract： Objective:To study the clinical efficacy of hyperbaric oxygen（HBO）combined with mild hypothermic therapy on children with severe traumatic brain injury（STBI）and its effect on secretion of pituitary-related hormones.Methods:The clinical data of 80 children with STBI admitted to Yuncheng Central Hospital from August 2016 to August 2021 were retrospectively analyzed. According to the different treatment methods，the children were divided into treatment group and control group，with 40 cases in each group. The control group was treated with mild hypothermic therapy，and the treatment group was treated with hyperbaric oxygen combined with mild hypothermic therapy. The cerebral edema volume，levels of pituitary-related hormones［growth hormone（GH），prolactin（PRL），adrenocorticotropic hormone（ACTH），thyroid-stimulating hormone（TSH）］and Glasgow coma scale（GCS）scores were compared between the two groups at admission and 3，5，7，and 10 days after treatment. After 6 months of follow-up，the prognosis of the two groups was compared.Results:There were significant differences in brain edema volume，GH，PRL，ACTH，TSH levels，GCS score at different time points，time points between groups，and interaction between groups（ P<0.05）. After 5，7，and 10 days of treatment，the cerebral injury edema volume and the levels of GH，PRL，ACTH，and TSH of the children in the treatment group were lower than those in the control group（ P<0.05），and the GCS score was higher than that in the control group（ P<0.05）. During the follow-up period，10 children died，including 3 in the treatment group and 7 in the control group. The average survival time of the children in the treatment group was longer than that in the control group，and the Log-Rank test showed that the differences were statistically significant（ χ2=4.091， P=0.043）. Conclusion:Hyperbaric oxygen combined with mild hypothermic therapy in the treatment of children with STBI can effectively reduce the cerebral injury edema volume，improve early pituitary-related hormone secretion disorders，thus improving the prognosis of children.