Objective：To compare the safety and efficacy of flexible ureteroscopy and percutaneous nephrolithotomy in the treatment of renal stones in patients with a solitary kidney. Methods：Clinical data of 20 cases of renal stones in a solitary kidney in our hospital between March 2010 and December 2016 were retrospectively analyzed. There were 8 cases of flexible ureteroscopy（FURS） and 12 cases of percutaneous nephrolithotomy（PCNL）. The stone size，operation time，decrease of hemoglobin，incidence of complication，length of postoperative hospitalization，stone-free rate（SFR），change in serum creatinine（Scr） were compared between the two groups. Results：There was no significant difference between the FURS and PCNL groups in operation time[（104.4±23.8） min vs. （125.0±55.4） min，t=0.988，P=0.336] and length of postoperative hospitalization[（4.3±2.6） d vs. （6.0±2.8） d，t=1.429，P=0.170]. The hemoglobin was decreased more significantly in FURS group than in PCNL group[-2.0（-6.0-8.0） g/L vs. 6.0 （-3.0-14.0） g/L，Z= -2.047，P=0.041]. Perioperative complications in two groups were ClavienⅠ to Ⅱgrade，including one case of fever and one case of systemic inflammatory response syndrome in FURS group，and 3 cases of fever，one case of systemic inflammatory response syndrome and one case of blood transfusion in PCNL group. There was no significant difference between the FURS and PCNL groups in postop－erative[（163.9±108.9） μmol/L vs. （161.0±56.2） μmol/L，t=-0.076，P=0.940] and preoperative Scr[（171.6±113.4） μmol/Lvs. （152.4±65.9） μmol/L，t=-0.470，P=0.644]. The SFR of FURS and PCNL group were 62.5%（5/8） and 75.0%（9/12），respectively. Conclusion：FURS has the same safety and efficacy as PCNL in the treatment of renal stones in patients with a solitary kidney. FURS is less traumatic and bleeding. PCNL has a higher SFR especially for staghorn stones in a solitary kidney.