Objective: To explore the efficacy and surgical techniques of ultrasound-assisted transurethral flexible ureteroscopic holmium laser incision and internal drainage in the treatment of special renal cystic diseases，so as to provide reference for the diagnosis and treatment of such diseases. Methods: The clinical data of 48 patients with special renal cystic diseases treated during Jan.2019 and May 2023 were retrospectively analyzed.The diagnosis was made by computed tomography urography (CTU) and three dimensional urinary tract reconstruction before operation.All patients received the abovementioned surgery in semisupine lithotomy position.The general information，clinical data，and incidence of complications were analyzed. Results: There were 27 males and 21 females，with an average age of (48.0±7.5) years，including 22 cases of parapelvic cysts，6 cases of endogenic simple renal cysts with an average diameter of (5.0±1.0) cm，and 20 cases of renal calyceal diverticulum with stones，with an average diameter of (2.5±1.3) cm for the diverticulum and an average diameter of (1.5±1.0) cm for the stones，which were located in the upper or middle calyces.In 7 cases，ureteroscopic localization was difficult，and the surgery was completed with percutaneous renal puncture needle assisted localization.Ureteral stenosis was detected in 2 cases during surgery，and surgery was performed 4 weeks after double J tubes were placed.The remaining operations were successfully completed.The average operation time was (42.0±14.5) minutes，and average hospital stay was (2.0±0.5) days.During the follow-up of (12.0±8.5) months，lumbar pain improved in 27 cases (100%)，renal cysts disappeared in 23 cases (82.1%,23/28)，cysts significantly reduced by ≥50% in 4 cases (14.3%,4/28)，slightly reduced by <50% in 1 case (3.6%,1/28)，and the renal calyx diverticulum disappeared in 20 cases (100%).Gross hematuria and lower back pain occurred in 2 cases，and no other complications developed. Conclusion: Ultrasound-guided transurethral flexible ureteroscopic holmium laser incision and internal drainage is a safe and effective treatment for special benign renal cystic diseases.When ultrasound-guided flexible ureteroscope localization is difficult to perform，percutaneous renal puncture needle may be applied.