Postoperative cognitive dysfunction (POCD) is a common and important complication after cardiac surgery. The pathological reactions caused by cardiac surgery, such as traumatic stress reaction, inflammation, hemodynamics disorders, and blood coagulation dysfunction, by triggering central inflammation, ischemia, hypoxia and ischemia-reperfusion injury and other mechanisms, leading to brain function-impairment, causing the development of POCD. According to the above mechanisms, taking corresponding protective measures, reducing the development of POCD, and improving the quality of life after cardiac surgery are of great importance.