Abstract： Objective To evaluate the surgical techniques and clinical efficacies of mini-percutaneous nephrolithotomy (mini-PCNL) for kidney stones in infants aged under 3 years.Methods A total of 319 children aged under 3 years (average:7-36 months) with kidney stone (average:1.0-4.5 cm) underwent mini-PCNL from December 2006 to December 2012.Their pre-operative/post-operative hemoglobin levels,hospital stay,operative duration and complications were retrospectively reviewed.Surgical indications included stone diameter ≥ 1 cm,hydronephrosis and recurrent urinary tract infections.The target calyx was punctured under the guidance of type B ultrasound and channel expanded to 14-16F.Then Holmium laser was used for shattering stones extracted under pediatric nephrolithotomy.Results All channels were successfully established.Complete stone clearance was achieved in 299 kidney units (93％).The procedures were simultaneous bilateral (n =12) and tubeless (n =35) mini-PCNL.Among 20 cases of residual stone,12 were self-discharged within 1 year and 8 extracted because of expanding within 1 year.The mean operative duration was 53-± 7.5 (31-135) min,mean hemoglobin decreased to 0.8-± 0.52 (0.2-1.46) g/dl,postoperative fever in 57/307(18.6％),perirenal fluid in 69/319(21.6％),ascites in 7/298(2.3％) and no blood transfusion.The average hospital stay was 6.3 (4-10) days.And 197 cases were followed up for 6-24 months and there was no stone recurrence or long-term complications associated with surgery.Conclusions Mini-PCNL has multiple advantages of less trauma,faster recovery and fewer complications,etc.Thus it is both safe and effective for kidney stones in infants aged under 3 years.