Background Animal experiments and clinical studies have shown that mild hypothermia (32 ℃-34℃) has significant neuroprotective effect against cerebral ischemia.The time (therapeutic time window) that when mild hypothermia begins and how long mild hypothermia persists for will determine whether neuroprotective effects are completely achieved.There is not an exact conclusion because the therapeutic time window is considered to depend upon the severity of the insult,depth of damage,and duration of cooling. Objective To review advances in research on therapeutic time window of mild hypothermia against cerebral ischemia. Content The concept of the therapeutic time window of mild hypothermia and the protection of mild hypothermia against cerebral ischemia is introduced.The mechanisms of early hypothermia and delayed hypothermia are discussed. Trend Clarifying these issues can be helpful to guide clinical treatment to cerebral ischemia.