In the last six months, more patients with congenital hydronephrosis due to pelvic ureteral junction stenosis have been consulted online. I would like to explain the cause and treatment of this disease, and hope that it will be of some help to patients. The most common cause of congenital hydronephrosis is primary obstruction of the ureteropelvic junction, which is caused by the lack of ureteral smooth muscle during development, resulting in impaired upper urethral dynamics, often leading to moderate to severe hydronephrosis, which in turn affects kidney function, and often combined with kidney stones in some patients due to slow urine flow and precipitation of crystals. For such patients, if the fluid accumulation reaches a certain level, or if the symptoms of back pain and swelling appear, surgery is required. Surgical treatment can be divided into two types: balloon dilatation or internal incision, which is performed through ureteroscopy or percutaneous nephroscopy to reach the pelvic ureteral junction, and then a special balloon is used to dilate the stenosis to 7-8 mm (normal ureteral internal diameter is 4-6 mm), or laser or electric knife is used to incise the stenosis and then a stent is placed to support it; the second type of surgery is Open or laparoscopic pyeloplasty, the most common of which is off-segmental molding, which requires complete removal of the stenotic segment and then anastomosis of the cut renal pelvis to the ureter. In terms of surgical results, the former procedure does not remove the stenotic segment, but only uses mechanical dilation or physical incision, and the scar formed after surgery is prone to re-stenosis, with a success rate of about 70-80%. The second procedure has a higher success rate of more than 90% due to complete removal of the stenotic segment. Laparoscopic pyeloplasty is the treatment of choice for primary pelvic ureteral junction stenosis, and generally requires only 3-4 holes to complete the procedure, which can be done via the transabdominal route or the retroperitoneal route, making the procedure much less invasive than open surgery. The pelvis and ureter are anastomosed so that the pelvic-ureteral junction becomes funnel-shaped, which facilitates the drainage of urine. Laparoscopic surgery has now become the gold standard for the treatment of primary pelvic ureteric junction stenosis.