Objective To analyze the causes of day surgery patients missing appointments, and discuss the countermeasures. Methods We selected the patients who had missed appointments for day surgery in the Second Affiliated Hospital Zhejiang University School of Medicine between January 2017 and June 2022. According to the implementation time of the measures, we divided the patients into two groups: pre-intervention (between January 2017 and June 2020) and post-intervention (between July 2020 and June 2022), to analyze the causes of patients’ cancellation, compare the change of patients’ cancellation rate before and after the implementation of measures, and explore the effectiveness of implementation measures. Results A total of 17 392 patients were included, and the total number of day surgery patients was 148 720 during the same period. The total cancellation rate was 11.69% (17 392/148 720). The cancellation rate in the post-intervention was lower than that in the pre-intervention [9.70% (7 935/81 775) vs. 14.13% (9 457/66 945), odds ratio was 0.695, 95% confidence interval (0.674, 0.717), P<0.001]. There were 13 common reasons for cancellation, of which “outpatient treatment, not hospitalization” was the most common reason. Conclusion Through the coordination of various departments, actively optimizing the preoperative evaluation of patients, updating the appointment process, strengthening effective communication and implementing the implementation of efficient medical treatment, the cancellation rate of day surgery can be reduced, which has certain reference significance to improving the management level of the hospital and the ability to serve patients.