Abstract： Objective To investigate the role of decompressive craniectomy (DC) to decrease the intractable intracranial hypertension(ICH) due to the diffuse brain swelling and/or cerebral edema after severe traumatic brain injury and the time window of DC to affect on the prognosis.Methods The clinical record of 132 patients who underwent DC for post- traumatic intractable ICH in our hospital from July 2003 to December 2009 with sTBI(Glasgow coma scale≤8) were analyzed retrospectively.The outcome was as measured by Glasgow Outcome Scale (GOS) at the 6th month post-trauma and these patients were divided into favorable group(GOS 4～5,n = 55 ),unfavorable group (GOS 2 ～ 3,n = 46) and Death (GOS 1,n = 31 ).The influence of DC on intracranial pressure (ICP),cerebral perfusion pressure (CPP) and timing of DC on prognosis were analyzed.Methods Of 132 patients,mortality was 23.5% (31/132 ),favorable outcome was observed in 41.7% (55/132 ).Through undergoing DC,ICP decreased from (35.0±12.8) mmHgto (18.3±12.0) mmHg(P＜0.05)and CPP increased from (50.2±12.4)mmHg to (60.6±12.0)mmHg(P＜0.05).These changes were more significant in survivors than in non- survivors (P=0.001 and P=0.003).No tendency towards either increased or decreased in favorable outcome and mortality was found relative to the timing of DC post-trauma.Persistent ICP≥25 mmHg of post- DC was a predicted parameter of mortality(sensitivity 81.6% ,specificity 92.4%,positive predictive value 68.4%,negative predictive value 94.7%).Conclusion DC deceased ICP and increased CPP more obviously in survivors compared to non-survivors in sTBI with ICH.The timing of DC showed no clear trend,for either good neurological outcome or death.The postoperative ICP ≥ 25 mmHg was a threshold to predicted mortality.