Purpose To evaluate the effect of potassium citrate administration on the composition of encrusted material on the ureteral stent after Double-J insertion. Methods We designed a randomized clinical trial for our study; 65 patients that underwent transurethral lithotripsy and Double-J stent insertion were included in the study after informed consent and divided into two groups. In the first group (33 patients) potassium citrate was prescribed after surgery till stent removal and the second group (32 patients) followed without prescribing this medication. After stent removal, encrusted materials on removed stents were analyzed then the type and composition of encrusted material compared with the primary stone that was removed. Results Our results revealed that the type and composition of primary stone and encrusted stone were similar in patients that do not receive potassium citrate ( p -value of 0.073, 0.251 and 0.944 for calcium oxalate, uric acid, and calcium phosphate respectively). In patients that taking potassium citrate rate of calcium oxalate ( p -value < 0.001) and uric acid ( p -value < 0.001) material on encrusted stent significantly decreased compared with the non-intervention group. Conclusion Results of this study revealed that taking of potassium citrate after ureteral stent insertion significantly decreases the formation of calcium oxalate and uric acid encrusted material on Double-J stent so it could be recommended for prevention of stent encrustation in patients that primary stone analysis are calcium oxalate and uric acid stone.