Objective To investigate the effect of mild hypothermia on neuroprotection and prognosis prediction of rats with traumatic brain injury (TBI) by dynamically monitoring the somatosensory evoked potentials (SEP) and quantitative electroencephalogram (QEEG).Methods Forty healthy adult male SD rats were randomly divided into four groups according to random number table,ie,normal control group (with no intervention),sham operation group (fenestration only,without drilling),TBI group (fluid percussion was used to produce moderate to severe TBI),and mild hypothemia group (ice blanket was used immediately after TBI for continuous physical cooling and rectal temperature was maintained at 32-35℃ and rewarmed to 37℃ 6 hours after the initiation of cooling),with 10 rats per group.Changes of SEP and QEEG in all groups were monitored at 6,24 hours,and 7 days after TBI.Results (1) Compared with TBI group,the latency of SEP waves (P1 and N1) on the injured side in mild hypothemia group began to shorten at 24 hours(P ＜ 0.05) and were close to that in the sham operation group at 7 days.(2) Except for normal control group and sham operation group,QEEG in TBI group showed decrease of α rhythm,increase of reactivity slow waves,and decrease or disappearance of QEEG relative power spectral values at all time points.In mild hypothermia group,the reactivity slow waves were decreased with a small amount of α wave; QEEG relative power spectral values were increased at 24 hours and 7 days (especially at 24 hours),but werc still lower than those in normal control group (P ＜ 0.05).Conclusion Mild hypothermia exerts neuroprotective effect through reducing SEP latency,raising relative power spectral values of QEEG,and improving the nerve conduction and brain electrical activity of the injured side.