Abstract: Cerebral tissue oxygen saturation (SctO2) monitor can monitor SctO2 noninvasively and continuously. SctO2 reflects the equilibrium state of oxygen supply and oxygen consumption in the brain tissue. Many factors can affect SctO2, such as cardiopulmonary dysfunction, cerebral tissue perfusion and metabolism, changes of blood components and pH, the physiological and pathological changes of intracranial vessels, drug, changes in body temperature and body metabolism, changes in body position and oxygen inhalation concentration during the operation. Therefore, SctO2 changes can be caused by diseases, clinical interventions, and surgery methods that can affect the above factors. Low SctO2 in the perioperative period can cause postoperative neurocognitive dysfunction (POCD), postoperative nausea and vomiting (PONV), delirium, and other complications. This article reviews the application of SctO2 in cardiac macrovascular surgery, carotid endarterectomy, single lung ventilation, orthopedic surgery, and Pediatrics, in order to provide reference for the clinic value and further research of SctO2.