Objective To study the effect of Sun’s end segment flexible ureterorenoscope in the treatment of complex renal calculi and its in?uence on renal function, so as to provide reference for clinical treatment. Methods From May 2020 to April 2022, 60 patients with complex renal calculi admitted to the Second Af?liated Hospital of Guangdong Medical University were selected and divided into the control group and the observation group according to the random number table, with 30 patients in each group. The patients in the control group were treated with percutaneous nephrolithotripsy, and the patients in the observation group were treated with Sun’s end segment ?exible ureterorenoscope. Compare the operation related indexes, cystatin C (Cys-C), β2-microglobulin (β2-MG), uric acid (UA), neutrophil gelatinase-associated lipocalin (NGAL),angiotensinⅠ(AngⅠ),angiotensin Ⅱ (Ang Ⅱ), high-sensitivity C-reactive protein (hs-CRP), tumor necrosis factor- α (TNF- α) levels and complications. Results The durations of operation, exhaust and hospitalization in observation group were signi?cantly shorter than that in control group, the amount of intraoperative blood loss was signi?cantly less than that in control group, and the stone clearing rate was signi?cantly higher than that in control group (P<0.05). After treatment, the levels of Cys-C, NGAL and β2-MG in two groups were signi?cantly higher than before treatment, while the level of UA was signi?cantly lower than before treatment (P<0.05). The levels of Cys-C, NGAL, β2-MG and UA in observation group were signi?cantly lower than those in control group after treatment (P<0.05). The levels of AngⅠ, Ang Ⅱ, hs-CRP and TNF-α in two groups after treatment were signi?cantly higher than before treatment, but the levels of Ang Ⅰ, Ang Ⅱ, hs-CRP and TNF-α in observation group was signi?cantly lower than that in the control group (P<0.05). The complication rate of observation group was signi?cantly lower than that of control group (P<0.05). Conclusion Sun’s end segment ?exible ureterorenoscope can effectively treat complex renal calculi, with a high stone removal rate, less damage to renal function, and a low risk of postoperative complications, which is worthy of clinical application.