【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.