Abstract: Postoperative cognitive dysfunction is a common complication after anesthesia and surgery, which increases the burden on the family and society. Since the discovery of orexin more than 20 years ago, a large number of studies have accumulated specific evidence indicating that orexin plays a key role in regulating cognitive function by affecting different brain regions. Nevertheless, the specific mechanism is still unclear. In this article, relevant studies analyzing the mechanism of orexin affecting cognitive function in recent years were reviewed, aiming to provide reference for the specific research of the role of orexin in preventing and improving cognitive function in the future.