After kidney stone surgery, a ureteral stent tube, also known as a double J tube, is routinely placed in the body. Its purpose is mainly twofold: 1. drainage. If the ureteral stent tube is not placed, the edema will lead to mucosal atresia, so that the urine produced by the kidney will be blocked and will accumulate in the kidney to form hydronephrosis, which can cause more obvious pain. After placing the double J tube, it can prevent the local mucosal edema from causing obstruction of the urinary tract, so that the urine in the kidney can be adequately drained and no hydrocele can occur, and no acute pain can occur. At the same time, for the already existing hydronephrosis, the placement of double J tube also has the purpose of draining the hydronephrosis and making the kidney’s morphology return to normal as soon as possible.2. Support. When the ureteral stent tube is placed, it can support the lumen of the tube and prevent the obstruction of the lumen caused by the discharged debris after the stone is broken. At the same time, it can also prevent the local mucosa from scarring later, causing ureteral stenosis, which can lead to secondary hydronephrosis, pelvic hypertension or severe back pain and other symptoms. If the ureteral stent tube is placed until the local inflammation is completely healed and the local scar of the ureter is stabilized, then it will not cause ureteral stenosis.