Background　Regional cerebral oxygen saturation(rSO2) monitoring is a new noninvasive method for monitoring cerebral oxygen balance. Intraoperative monitoring of rSO2 in elderly patients can optimize perioperative management of elderly patients and reduce the incidence of postoperative neurological complications.　Objective　To provide reference for the related research and clinical application of rSO2 monitoring.　Content　This paper introduces the basic principle and influencing factors of rSO2, and the application of rSO2 in cardiac surgery, neurosurgery, thoracic surgery, abdominal surgery and orthopedics in elderly patients.　Trend　Further research is to explore the application value of rSO2 in elderly patients and reduce the postoperative complications of elderly patients.