Objective To analyze the causes of unplanned reoperation,provide the basis for perioperative quality manage-ment,improve medical quality and ensure medical safety.Methods All 6 840 hospitalized patients from January 2019 to December 2022 were selected as the study objects,combined with the surgical information collected by the medical record statistics system,retrospective analysis of all unplanned reoperation cases during the same period.Results There were 30 cases of unplanned reoperation,all of which were grade Ⅲ and Ⅳ operations,and the incidence of unplanned reoperation was 0.439%.The incidence of unplanned reoperation in orthopedics was higher than that in general surgery and obstetrics and gynecology,and the difference was statistically significant(P<0.017).The reasons leading to unplanned reoperation in-clude the level of operation,the type of disease admitted,the infection of the operative area,and perioperative management.Conclusion Strict implementation of surgical classification management system,hospital sense control,strengthening peri-operative quality management and improving surgical skills can reduce unplanned reoperation and achieve continuous improvement of medical quality.