Dexmedetomidine，as a highly selective 2 adrenergic receptor agonist，has sedative，analgesic and stress-relieving effects. A large number of studies have confirmed that the perioperative application of dexmedetomidine not only has an auxiliary analgesic effect， but also can reduce the dosage of other analgesic drugs，reduce its adverse reactions，and enhance its analgesic effect，so as to improve the perioperative comfort of patients，maintain hemodynamic stability，and reduce postoperative pain. This article reviews the action mechanism of dexmedetomidine and the effect of dexmedetomidine on perioperative analgesia.