Objective To analyze the influencing factors of unplanned readmission for day surgery patients under the centralized management mode, and to provide a scientific basis for improving the medical quality and safety of day surgery. Methods The data of patients in the day surgery ward of the Second Affiliated Hospital Zhejiang University School of Medicine between October 2017 and October 2021 were retrospectively collected, and they were divided into an unplanned readmission group and a control group according to whether they were unplanned readmission within 31 days. Multivariate logistic regression model was used to analyze the influencing factors of patients’ unplanned readmission within 31 days. Results There were 30 636 patients, of which 46 were unplanned readmission patients, accounting for 0.15%. Logistic regression analysis showed that male [odds ratio (OR)=0.425, 95% confidence interval (CI) (0.233, 0.776), P=0.005], thyroid surgery [OR=19.938, 95%CI (7.829, 50.775), P<0.001], thoracoscopic partial lobectomy [OR=13.481, 95%CI (5.835, 31.148), P<0.001], laparoscopic cholecystectomy [OR=10.593, 95%CI (3.918, 28.641), P<0.001] and hemorrhoidectomy [OR=13.301, 95%CI (4.473, 39.550), P<0.001] were risk factors for unplanned readmission in patients undergoing day surgery. Conclusion Medical staff in day surgery wards need to strengthen supervision of male patients and high risk surgical patients, and improve patients’ awareness of recovery, so as to reduce the rate of unplanned readmission.