© 2021 John Wiley & Sons LtdAims: To compare the efficacy of different laser devices and power ranges on lithotripsy in retrograde intrarenal surgery (RIRS) for 1-2 cm kidney stones. Methods: A total of 223 participants undergoing RIRS for 1-2 cm kidney stones at our clinic between January 2015 and January 2017 were recruited for this prospective study (NCT02451319). Two hundred and four participants included in our study were randomly allocated into either ≤20 W with 20 W laser device (group 1) or ≤20 W with 30 W laser device (group 2) or >20 W with 30 W laser device (group 3). Results: There was no significant difference between the groups in terms of demographic and stone characteristics. Operation and fluoroscopy times were significantly longer (P =.003 and P <.001, respectively) and stone-free rate (SFR) was significantly lower in group 1 (P =.002). Complications were similar in all three groups (P =.512). However, post-operative pain scores were significantly higher in group 1 (P <.001). The multivariate analysis revealed that stone size (95% CI: 0.654-0.878, OR = 0.758, P <.001), ureteral access sheath use (95% CI: 1.003-20.725, OR = 4.560, P =.049), and lithotripsy with 30 W laser device (95% CI: 1.304-11.632, OR = 3.895, P =.015; 95% CI: 1.738-17.281, OR = 5.480, P =.004, groups 2 and 3, respectively) were independent factors predicting SFR for RIRS used in 1-2 cm kidney stones. Conclusion: The 30 W laser device used in RIRS for 1-2 cm kidney stones had shorter operation times, higher SFRs, and lower post-operative pain scores compared with the 20 W device. The 30 W laser device is safe and more efficient in RIRS for treatment of 1-2 cm kidney stones.