Objective: To investigate the feasibility, safety and effectiveness of robot-assisted laparoscopic buccal mucosa graft ureteroplasty in the treatment of complex long proximal ureteral stricture. Methods: The clinical data of 20 patients with proximal ureteral stricture undergoing robot-assisted laparoscopic buccal mucosa graft ureteroplasty admitted to the Department of Urology, Peking University First Hospital and Beijing Jiangong Hospital from July 2022 to January 2023 were prospectively collected and analyzed. Intraoperative conditions, postoperative complications and follow-up data were also recorded and analyzed. Results: The operations under robot-assisted laparoscopy were performed successfully in all the 20 patients without conversion to traditional laparoscopic surgery or open surgery. The study included 14 males and 6 females with a mean age of (41±11) years (range: 19 to 60 years) and a mean body mass index of (24.3±3.6) kg/m² (range: 18.2 to 31.8 kg/m²). There were 9 cases on the left side and 11 cases on the right side. The strictures of all the patients were located in the proximal segment of the ureter (including the ureteropelvic junction). The mean preoperative serum creatinine was (92.2±23.3) μmol/L (range: 49.2 to 138.9 μmol/L), and the mean length of ureteral stricture was (2.8±0.9) cm (range: 1.0 to 4.0 cm). Ten patients had previously undergone unsuccessful reconstructive surgery. During the operation, 12 patients received posteriorly augmented anastomosis with ventral onlay. The mean length of the buccal mucosa graft harvested during the operation was (3.1±0.6) cm (range: 2.0 to 4.3 cm), and the median width was 1.5 cm (range: 1.0 to 2.0 cm). The omentum flap was used to wrap the reconstructed ureteral segment in all the 20 cases. The median operative time was 154 min (range: 113 to 300 min), and the median estimated blood loss was 45 mL (range: 0 to 100 mL). The median postoperative hospital stay was 4 d (range: 4 to 14 d). The mean postoperative follow-up time was (15.0±1.7) months (range: 12.5 to 17.9 months), and the surgical success rate was 100.0% in this study. After surgery, 11 patients reported mild discomfort at the oral donor site, 2 patients deve-loped urinary tract infection, and no postoperative complications were reported in the other 7 patients. The mean serum creatinine was (90.9±23.9) μmol/L (range: 60.0 to 153.0 μmol/L) six months after surgery. Conclusion: Robot-assisted laparoscopic buccal mucosa graft ureteroplasty for the treatment of complex long proximal ureteral stricture has satisfactory efficacy without severe complications, which has shown good feasibility, safety and effectiveness. However, large sample studies and long-term follow-up are still needed to evaluate its long-term efficacy.