Objective To explore related influencing factors for postoperative delirium in elderly patients, to provide a reference for the prevention and treatment. Methods Fifty-four patients with delirium after surgery were used as observa?tion group, and a total of 150 subjects with no delirium after surgery during the same period were selected as the control group. Data of age, gender, malnutrition, disorders of water and electrolyte metabolism, postoperative mechanical ventilation, postoperative hypoxemia, severe infection and postoperative pain degree, and the combination of basic diseases were com?pared and analysed between two groups. The binary logistic regression analysis was used to analyse the influencing factors of postoperative delirium. The outcome and prognosis were observed and analyzed in observation group. Results The average age was significantly higher in observation group than that of control group (P<0.05). The percentages of postoperative hy?poxemia and severe infection were significantly higher in observation group than those of control group ( P<0.05). Patients with higher age, postoperative hypoxemia and severe infection were risk factors for postoperative delirium. In observation group,1 case died of lung infection, 1 case died of multiple organ failure, the remaining 52 patients were improved and dis?charged from hospital after three months. Conclusion For patients with higher age, postoperative hypoxemia and severe in?fection are the risk factors for occurrence of postoperative delirium. More attention should be paid to clinical preoperative and postoperative periods.