OBJECTIVE: To investigate the clinical treatment effect of F8 combined ureteral flexible microscope for upper urinary tract stones, and to evaluate the factors influencing the success rate of ureteral flexible microscope lithotripsy and surgical technique. METHODS: We retrospectively analyzed the clinical data of 56 patients with upper urinary tract stones treated by laser lithotripsy with the combined ureteral chondroscope from October 2012 to May 2013 in our hospital. The maximum diameter of the stone was 2.0 cm, and the location of the stone: 12 cases were located in the pelvic ureteral junction; 15 cases were located in the middle calyx; 17 cases were located in the upper calyx, 7 cases were located in the lower calyx, and 5 cases were located in multiple calyces (middle calyx + lower calyx). Five cases had ureteroscopic placement of D-J tubes for 2 to 8 weeks due to hydronephrosis and infection. Under general anesthesia or continuous epidural anesthesia, the patient was placed in the lithotomy position, and the affected ureter was first explored with the F8/9.8 Wolf ureteroscope under the guidance of a zebra guidewire. If the rigid ureteroscope could not be inserted successfully, a double J tube was left in place and a second stage ureteroscopic lithotripsy was performed 2 weeks later. The U100FREDDY laser or Holmium laser is used for lithotripsy. The F5-7 double J tube was routinely left in place for 2-4 weeks. The catheter was removed on postoperative day 1-3, and broad-spectrum antibiotics were routinely given intravenously for 2 days. 4 weeks later, the KUB or CT scan of both kidneys was reviewed to assess the stone clearance rate, and a residual stone of 4 mm was considered as a meaningful stone residue. Results: The success rate of primary access was 91.1% (51/56), and the remaining 5 cases with failed access were successfully accessed after 2 weeks with the placement of a double J tube with a guide wire. The stone clearance rate was 85.7% after 4 weeks (48/56), 91.8% (45/44+5) in the middle and upper renal calyces and pelvis, and 58.3% (7/7+5) in the lower renal calyces. 5). There was no ureteral perforation or bleeding. The average operation time was 45 min (25-75 min). 1 case developed bacteraemia, which was cured after anti-inflammatory symptomatic treatment, and the postoperative carnal hematuria disappeared within 1~2 days. Those who failed to laser lithotripsy took ESWL or wait for observation treatment after surgery. CONCLUSION: F8 combined ureteroscope combined with FREDDY laser or holmium laser is a safe and effective means to manage <20 mm kidney stones. Stones in the middle and upper renal calyces and renal pelvis had higher stone finding rate, higher success rate of lithotripsy, and higher stone removal rate than stones in the lower renal calyces. Patients with difficulty in accessing the ureteroscope in the first stage can undergo soft ureteroscopic lithotripsy in the second stage after 2 weeks of indwelling double J tube.