The present multi-center, randomized controlled trials is designed to investigate the efficacy and safety of long-term (5 days) mild hypothermia versus normothermia on the outcome of patients following severe traumatic brain injury. The primary outcome is the neurological function assessed at 1, 6 months post injury with the Glasgow Outcome Score (GOS). Additionally, the following data will also be recorded and compared: the baseline data, Glasgow Coma Score,imaging examination (e.g. CT scan), need of surgery, intracranial pressure, laboratory tests (e.g. blood routine test, liver and kidney function, blood gas analysis, etc), the complications (e.g. pneumonia, significant bleeding) and so on.