Abstract: Objective To observe the changes in intracranial pressure (ICP) and brain tissue oxygen tension (PO₂) and their significance in severe head injury treated by moderate hypothermia (33-35℃). Methods Eighteen patients with severe head injury were treated with moderate hypothermia group and probes were deployed in the cerebral cortex for measuring their ICP and PO₂ under continuous monitoring. Another 14 similar patients receiving the same treatment but without hypothermia served as the control group. Results In moderate hypothermia group the ICP gradually decreased and PO₂ increased after 24 hours of hypothermia, with obvious difference from the control group (P<0.05). Conclusion Moderate hypothermia can obviously reduce ICP and improve brain tissue oxygen metabolism to lower the morbidity and mortality rate of severe head injury.