Mild hypothermia therapy shows protective effects for damaged brains of animals and post cardiac arrest patients. However, Clifton et al. reported that mild hypothermia has no protective effect for severe head trauma but has a risk of complications. In this study, all the participants must be treated with continuous monitoring of cardiac output and jugular venous oxygen saturation to get optimal physiological conditions. Adequate anesthesia such as neuroleptanesthesia is essential to maintain organ function and tissue microcirculation. Participants are randomly assigned to two groups of mild hypothermia (32.0 - 34.0 degree Celsius) and anti-hyperthermia (35.5 - 37.0 C). The body temperature must be kept for at least 72 hours. Hypothermia must be induced within 6 hours after traumatic brain injury. Glasgow outcome score at 6 months after injury and the total medical expenses of the two groups will be evaluated.