Objective To investigate the micro -channel percutaneous nephrolithotomy under ultrasound guidance in clinical studies of renal calculi in non -dilated collecting system.Methods Clinical data of 126 patients with renal calculi in non -dilated collecting system treated by ultrasound -guided percutaneous nephrolithotomy microchannel were retrospectively analyzed.Ureteroscopy up to the renal pelvis or ureter segment,zebra guide wire was placed along the guide wire indwelling ureteral catheter end connected to the blood transfusion needle while external saline suspension 100cm.Ultrasound -guided puncture target cup,established 16 -18F channel percutaneous nephro-lithotomy,ureteroscopy downlink percutaneous nephrolithotomy lithotripsy.The clinical data of operation time,stone clearance rate,blood loss,complications were analyzed.Results 124 patients with successful puncture,puncture fail-ure in two patients,conversion to open surgery.118 cases of successful implementation of a single -channel stone, nine cases of postoperative residual stones was found,again two stone surgery in 6 cases,3 cases refused surgery again;six cases were due to stones larger load,operation time exceeded 2h,to 2 stage of stone surgery in 4 cases, 2 cases changed to standard channel.Operation time was 30 -150min,average 78min.A stone clearance rate was 87.3%,summarize stone clearance rate was 95.2%(118 /124).Postoperative hemoglobin level decreased to (16.0 ± 7.6)g/L,7 patients with postoperative bleeding more blood transfusion 400 -800mL,none embolization.4 cases of postoperative fever,septic shock in 1 case,1 case of pneumothorax.Conclusion The micro -channel percutaneous nephrolithotomy under ultrasound guidance in the treatment of renal calculi in non -dilated collecting system is safe and feasible,it is the preferred method of treating renal calculi in non -dilated collecting system.