Perioperative neurocognitive disorders are common postoperative complications in the elderly after surgery, which not only prolong the length of hospital stay but also enhance economic burden. What′s more, their occurrence may be related to inflammatory response, blood-brain barrier damage, central nervous system inflammation, microglia activation, oxidative stress, and activation of central nervous system related pathways and neurotransmitter releaseinduced by aseptic surgery or anesthesia surgery. Dexmedetomidine is a selective alpha 2 adrenal agonists and widely used in clinical practice since being approved by the U.S. Food and Drug Administration, and shows protective effects on important organs such as the heart, brain and kidneys. At present, evidence shows that dexmedetomidine has certain effect on reducing perioperative cognitive impairment, but more researches are needed in the future to explore its long-term impact on cognitive function.