Objective To investigate the efficacy and safety of a tip-flexible suctioning ureteral access sheath combined with a flexible ureteroscope under local anesthesia in the treatment of high-burden kidney stones with a diameter of ≥3 cm. Methods A retrospective analysis was performed for the clinical data of the patients with kidney stones with a diameter of ≥3 cm who underwent holmium laser lithotripsy by ureteral ureteroscopy under local anesthesia in Department of Urology，The First Affiliated Hospital of Chongqing Medical University，from January to December 2023，and the patients were divided into flexible sheath group and conventional sheath group. General data were collected，and the two groups were compared in terms of perioperative indicators，postoperative complications，and surgical outcomes. Results A total of 96 patients were enrolled in this study，with 44 patients in the flexible sheath group and 52 patients in the conventional sheath group. There were no significant differences between the two groups in the general data such as age，body mass index，and stone burden，and compared with the conventional sheath group，the flexible sheath group had a significantly higher postoperative stone clearance rate（72.73% vs. 46.15%，P<0.05），while the complication rates，such as fever（2.27%） and stone street formation（2.27%） were significantly lower than that of the traditional sheath group（23.08%/17.31%），P<0.05，There was no significant difference in the time of single operation between the flexible sheath group and the conventional sheath group（126.20±21.45 min vs. 116.71±27.39 min）. Conclusion Tip-flexible suctioning ureteral access sheath combined with flexible ureteroscopy under local anesthesia is safe and effective in the treatment of high-burden kidney stones with a diameter of ≥3 cm and thus holds promise for clinical application.