How big a stone in the lower calyces of the kidneys is before it becomes painful is not strictly stated clinically, and kidney stones may induce renal colic regardless of their size. Kidney stones are crystalline substances (e.g. calcium, urate, oxalate, etc.) that precipitate from the urine and are deposited in the kidneys, which belong to the urinary tract stones. Some patients with small infrarenal calyx stones, such as 3~4mm may cause pain, and some patients with larger infrarenal calyx stones, such as more than 10~20mm, feel pain only. However, as long as there are kidney stones, it is possible to cause the attack of renal colic in patients. Usually smaller kidney stones have a greater range of motion and are more likely to induce renal colic. The onset of infrarenal calyces stones may be related to a variety of factors such as lifestyle and metabolic abnormalities, and the most prominent clinical symptoms are pain in the renal region and hematuria. If kidney stones are not treated promptly and actively, they can easily lead to obstruction of the urinary tract, which in turn leads to infection, and in serious cases, can lead to renal failure. If patients are diagnosed with lower calyceal stones, they should actively cooperate with the doctor’s treatment regardless of whether they have pain symptoms or not, in order to prevent the condition from worsening.