Dexamethasidine (DEX) is an alpha-2 adrenoreceptor (α₂-AR) agonist, which is not only used in the perioperative period, but also in outpatient examination or treatment. The characteristics and advantages of sedation and hypnosis with DEX are that patients can enter a state similar to natural sleep, which is not only beneficial to improve the sedation effect, but also easy to wake up, and there is little jaw relaxation and no obvious respiratory inhibition. The additional advantages of DEX lie in its function of anti-stress response and potential organ protection and its little influence on cognitive function. The main adverse reactions of DEX were temporary hypertension, hypotension, bradycardia, and so on. Another characteristic of DEX is the relatively slow disappearance of drug effect. Patients may have drowsiness and postural hypotension after operation. It must be noted that DEX cannot be used as an independent anesthetic in general anesthesia to act as the main analgesic and sedative, but only to play an auxiliary role, which depends on the reasonable use and dosage and is not "all" or "none". And the vital signs of patients must be closely monitored during the process of DEX application.