Objective To investigate the safety and efficacy of flexible ureteroscope combined with flexible terminal suction ureteral access sheath in the treatment of impacted ureteral calculi with a diameter of ≥1.5 cm，and to summarize related clinical experience. Methods A retrospective analysis was performed for the clinical data of 27 patients with impacted ureteral calculi with a diameter of ≥1.5 cm who received flexible ureteroscope combined with flexible terminal suction ureteral access sheath in The First Affiliated Hospital of Guangxi Medical University from January 2023 to February 2024. Results A total of 27 patients were enrolled，among whom there were 23 male patients and 4 female patients，with a mean age of （48.4±15.4） years and a mean body mass index of （23.7±3.2） kg/m². Of all 27 patients，19 had ureteral calculi at the left side and 8 had ureteral calculi at the right side. The CT value of stones was （1097.6±268.7） HU. The mean length and width of calculi were （1.8±0.3） cm and （0.9±0.2） cm，respectively. As for the location of calculi，24 patients had upper ureteral calculi，2 had middle ureteral calculi，and 1 had lower ureteral calculi. There were 5 patients with ipsilateral renal calculi and 22 without renal calculi. The mean depth of hydronephrosis was （4.7±1.8） cm. There were 2 patients with negative preoperative urine white blood cells，13 with weakly positive（+） urine white blood cells，7 with positive（++） urine white blood cells，and 5 with strongly positive（+++） urine white blood cells. A total of 25 patients completed flexible ureteroscopy，and 2 patients changed the surgical procedure during surgery，with a mean time of operation of （86.7±46.4） minutes and a mean length of hospital stay of （3.1±1.7） days. The levels of white blood cells and hemoglobin were （8.0±2.4）×10⁹/L and （135.1±21.4） g/L，respectively，before surgery，and （8.9±2.5）×10⁹/L and （135.9±17.8） g/L，respectively，on day 1 after surgery. Reexamination on day 1 after surgery showed that 22 patients had no residual stones，while 5 had residual stones. The mean body temperature on the day after surgery was （36.2±0.2） ℃，with no clinical manifestations of urinary sepsis. Conclusion Flexible ureteroscope combined with flexible terminal suction ureteral access sheath is safe and effective in the treatment of impacted ureteral calculi with a diameter of ≥1.5 cm，with a relatively high stone clearance rate and a relatively low incidence rate of complications.