Abstract： Objeetive To explore the causes and prophylactic therapeutic interveutions of acute intraoperative encephalocele in severe traumatic brain injury.Methods The clinical data of acute intraoperative encephalocele in fifty-six patients with severe traunatic brain injury were analyzed retrospectively.Results Delayed intracranial hematomas,acute diffuse brain swelling,cerebral anoxia and massive brain contusion and laceration were the main causes of intraoperative encephalocele.Intraoperative hyperventilation,complete removal of hematomas to decrease intracranial pressure gradually should be the methods for treatment.Twenty-five patients were died (45％).The prognosis of the survivors were evaluated according to Glasgow Outcome Scale (GOS) at 8 months after operation,6 cases of patients showed a good outcome (14％),10 moderately disabled (18％),11 severely disabled (19％),2 permanent vegetative state (4％).Conclusions Treatment exerted according to different causes could improve the effects and the prognosis of acute intraoperative encephalocele patients with severe traumatic brain injury.