Objective：To assess the efficacy and safety of flexible ureteroscopy retrograde surgery（fURS） for the treatment of uri－nary calculi over 2 cm in diameter. Methods：The data of 272 patients who underwent fURS by standard techniques for urinary cal－culi over 2 cm was collected retrospectively. Demographic，intraoperative，and postoperative data were reviewed and compared to e－valuate the efficacy and safety and to find statistically significant differences. Results：Totally 272 patients（male 188，female 84） were enrolled including 254 cases of renal stone，18 cases of upper ureteral stone and 6 cases of renal stone combined with ureteral stone，and the median age of all patients was 46.5. The cumulative stone diameter（CSD） was （34.2±9.7） mm. Overall stone free rate within 30 days was 90.5%，and overall stone free rate within 90 days was 93.8%. The incidence of complications was 10.3%，including fever in 12 cases（4.4%），steinstrasse in 2 cases（0.7%），hematuria over 24 hours in 7 cases（2.6%） and backache in 7 cases（2.6%）. Logistic regression indicated that hydronephrosis was an independent factor affecting stone clearance（95%CI=5.31 to 7 133.90，P=0.004），and the operation time was the factor affecting the complication rate（95%CI=1.030 to 1.222，P=0.008）. Conclusion：Flexible ureteroscopy is an effective and safe management method for over 2 cm urinary stones. Hydronephrosis may affect the stone free rate，and operation time may affect the complication rate.