Objective To compare the safety and efficacy of flexible terminal suction ureteral access sheath(FTS-UAS)and negative pressure ureteral access sheath(NPUAS)in flexible ureteroscopic lithotripsy with holmium laser in treatment of renal calculi less than 2 cm in diameter.Methods A total of 68 patients(largest diameter of stone＜2 cm)with renal calculi treated in Yangjiang Hospital Affiliated to Guangdong Medical University during Nov.2022 and Aug.2023 were divided into FTS-UAS group(n=34)and NPUAS group(n=34)according to different surgical methods.The perioperative parameters and stone-free rate(SFR)were compared between the two groups.Results The average SFR on the first day after operation was significantly higher in the FTS-UAS group than in the NPUAS group[85.3％(29/34)vs.61.8％(21/34),P=0.028].The operation time was significantly lower in the FTS-UAS group than in the NPUAS group[(65.85±13.16)min vs.(75.59±20.21)min,P=0.022].For lower calyceal renal calculi,the SFR was significantly higher in the FTS-UAS group than in the NPUAS group[82.4％(14/17)vs.43.8％(7/16),P=0.032].One month after operation,the SFR was higher in the FTS-UAS group than in the NPUAS group[94.1％(32/34)vs.85.3％(29/34),P=0.452].There were no significant differences in hemoglobin reduction,serum creatinine level,postoperative complications,hospital stay and hospitalization costs between the two groups(P＞0.05).Conclusion FTS-UAS in flexible ureteroscopic lithotripsy can shorten the operation time and improve stone-clearance rate,which is safe,effective,and worthy of clinical promotion.