Objective To evaluate the clnical value of percutaneous nephrolithotomy combined with flexible cystoscope in the treatment of complicated renal calculi.Methods Data of 53 cases of complex renal calculi treated with single channel percutaneous nephrolithotomy combined with flexible cystoscope from July 2011 to September 2013 were analyzed retrospectively.There were 31 males and 22 females.Their age ranged from 26 to 74 years with a mean age of 49 years.Thirty-two cases were located on the left side,19 cases right,2 cases bilateral,21 cases of staghorn calculi and 32 cases of multiple stones.All the stones were filled in 2 or more calyces,with 7 cases in upper ureteral stones at the same time and 2 cases in solitary kidney.The longest diameter of stones was between 2.5 cm to 4.6 cm,with an average of 3.7 cm.There were 39 cases with hydronephrosis and the separation of the collection system was 2.0-5.1 cm with an average of 3.8cm.The period which patients suffered from stones was from 1 month to 6 years.Fourteen cases underwent ESWL and 6 cases underwent open operation before percutaneous nephrolithotomy.All patients underwent single channel percutaneous nephrolithotomy under the guidance of color Doppler ultrasound,and the channel of puncture was expanded to 24 F.Results Fifty-three cases (55 sides) were performed successfully in one-stage sugery and the operation time was between 85 to 170 min,with an average of 119 min.The stone clearance rate was 89% (49/55) and postoperative hemoglobin decreased 3.9-9.2 g/L with an average of 6.1 g/L.The hospitalization time was 8 to 12 days with an average of 9.2 days.Two cases had hemorrhage of about 500 ml after surgery and the renal hemorrhage stopped after clamping of renal fistula without blood transfusion.Two patients suffered from fever on surgery day and 1 patient on one day after surgery,and the body temperature returned to normal level after anti-infection treatment for 2 or 3 days.No renal perforation,fluid pneumothorax or damaged surrounding organs occurred.6 patients had residual stones,among which 2 were treated by two-stage operation and 4 were treated with extracorporeal shock wave lithotripsy.Conclusion Percutaneous nephrolithotomy combined with flexible cystoscope has little trauma and high stone clearance rate in the treatment of complex renal calculi with high clinical value. Key words: Percutaneous nephrolithotomy; Flexible cystoscope; Complex renal calculi