Objective: To compare the clinical efficacy of mini percutaneous nephrolithotomy (mPCNL) and super mini percutaneous nephrolithotomy (SMP) in the treatment of single pediatric renal pelvis stones with CT value ≤ 800 HU，to provide reference for the diagnosis and treatment of children with such low-density stones. Methods: The clinical data of 74 children with single renal pelvis stones (1.0—2.5 cm in size，CT value ≤ 800 HU) treated in our hospital during Jan.2015 and Dec.2021 were retrospectively，with the subjects divided into mPCNL group (n=39) and SMP group (n=35) based on the surgical methods.The operation time，decrease in hemoglobin 2 hours after surgery，hospital stay，stone clearance rate，tubeless rate，and the incidence of complications (fever，mild renal pelvis injury) were compared between the two groups. Results: The operation time [(45.5±20.1) min vs. (59.8±13.6) min，P<0.001] and average hospital stay [(7.1±1.4) d vs.(11.1±2.6) d， P<0.001] were shorter in the SMP group than in the mPCNL group，while the tubeless rate (68.6% vs. 10.3%，P<0.001) was higher.There were no significant differences in the hemoglobin 2 hours after surgery and stone clearance rate at 1 month after surgery between the two groups (P>0.05).No blood transfusion was required in either group.Fever (≥38.5 ℃) occurred in 1 case and mild renal pelvis perforation occurred in 2 cases in the SMP group，while fever occurred in 2 cases and mild renal pelvis perforation occurred in 3 cases in the mPCNL group，with no significant difference between the two groups (8.6% vs.12.8%，P=0.556). Conclusion: The mPCNL and SMP have comparable efficacy in the treatment of single pediatric renal pelvis stones with CT value ≤800 HU，but SMP has advantages of shorter operation time，shorter average hospital stay，and higher tubeless rate.