Postoperative delirium (POD) is a common complication after surgical anesthesia in elderly patients, especially after major surgery or emergency surgery, which interferes with the recovery process of patients and the prognosis of the primary disease, and may cause new complications to prolong the hospitalization cycle, increase the fatality rate and increase the medical cost of patients. Because the mechanism of POD is not clear, there is a lack of effective prevention measures. Recent studies have shown that Dexmedetomidine (DEX), as a highly selective α2 adrenergic receptor agonist, has shown certain advantages in POD prevention and treatment. In this paper, the related mechanisms and risk factors of POD, the clinical studies of dexmedetomidine in the prevention and treatment of POD in elderly patients and its potential mechanisms were reviewed, aiming to provide theoretical basis for clinical application.