The elderly patients have poorer overall conditions and have lower tolerance to trauma, anesthesia, and surgery. Therefore, the incidence of postoperative complications is relatively higher. In non-cardiac surgeries, approximately 20% of elderly patients experience postoperative complications, and the incidence of postoperative delirium (POD) is 23.8%. This may lead to prolonged hospital stays, increased hospital costs, and affect prognosis and even mortality. The investigators plan to conduct a prospective cohort study by systematically collecting biological samples and clinical information of elderly patients during the perioperative period to explore the possible risk factors and pathogenesis of postoperative delirium and postoperative complications in elderly surgical patients, and to construct a risk prediction model for postoperative complications.