Abstract：Objective To observe the effect of potassium sodium hydrogen citrate granule on the wall stone shell of preset ureteral stent before ureteroscopy. Methods A total of 263 patients with pre-operative ureteral stents for renal calculi treated in our hospital from January 2019 to June 2021 were studied retrospectively, of which 129 patients who took oral potassium sodium citrate granules from the pre-operative ureteral stents to the pre-operative ureteroscopy were classified as the experimental group, while 134 patients who did not take any drugs were classified as the control group. Both groups of patients returned to the hospital for ureteroscopic lithotripsy after 3 weeks according to the doctor's advice. After pulling out the ureteral stent tube during the operation, the two doctors observed whether there was wall attached stone shell on the surface of the ureteral stent tube and the thickness of the stone shell, and recorded it in a special notebook after unified opinions. The weight of ureteral stent and completely scrape off the stone shell were counted to obtain the weight of stone shell. Results In the experimental group, 129 ureteral stents were pulled out, of which 7 showed thin stone shells and 4 showed thicker stone shells（the thickest part ≥ 1mm）. The stone shell formation rate was 8.53%, and the average stone shell weight was （0.8521 ± 0.1952）g. In the control group, 134 ureteral stents were pulled out, including 21 thin stone shells and 9 thick stone shells. The stone shell formation rate was 22.39%, and the average stone shell weight was（1.7823 ± 0.1802） g. The ureteral stent was pulled out at one time in both groups. The formation rate of stone shells in the experimental group was lower than that in the control group, and the number of thicker stone shells was less than that in the control group, and the differences between the two groups were statistically significant（χ2＝8.5717, 9.7144, all P＜0.05）; The weight of stone shells in the experimental group was lower than that in the control group, and the difference between the two groups was statistically significant（t＝－40.143, P＜0.05）. Conclusion Potassium sodium hydrogen citrate granules can be used as an economic， effective and safe drug to reduce the formation of stone shell attached to the wall of ureteral stent and slow down the progress of stone shell thickness, which is worthy of clinical promotion.