PurposeThe goal of this study is to evaluate the efficacy and safety of modified triangular double-J (DJ) stent in 1-2 cm renal or ureter calculi after retrograde intrarenal surgery (RIRS) via a randomized, controlled clinical study.MethodsA total of 196 patients with 1-2 cm renal or ureter calculi who were performed RIRS and received 7Fr modified triangular DJ stents (100 cases) or 6Fr normal DJ stents (96 cases). All operations were performed by experienced surgeons. The clinical characteristics and outcomes were analyzed.ResultsThere were no significant differences between two groups in terms of age, gender, BMI, location, hydronephrosis, urea WBC, urea RBC, BUN, Cr, laser emission time, operation time, Hb loss, postoperative BUN, postoperative Cr. Patients who received modified triangular DJ stents were shown to have higher stone-free rate (p = 0.038), but lower general health (p = 0.004).ConclusionThe modified triangular 7Fr DJ stents were more efficient for patients underwent RIRS than 6Fr normal DJ stents.