The causes of hydronephrosis in babies are directly related to congenital pelvic ureteral junction stenosis, ureteral stone, bladder outlet obstructive disease. After the onset of hydronephrosis, we need to combine the causes of hydronephrosis with the methods of open surgical treatment and cystoscopic retrograde ureteral cannula drainage and other methods of treatment. 1. Congenital pelvic ureteral junction stenosis: many babies with hydronephrosis have congenital pelvic ureteral junction stenosis, which belongs to congenital problems and can be treated by surgery, but open or laparoscopic surgery should be chosen in accordance with the actual situation of the baby, and the stenosis can be relieved only by surgery at an early stage. 2. Ureteral stones: if the baby has ureteral stones, it will cause obstruction symptoms, which need to use cystoscopy retrograde ureteral tube drainage, open or laparoscopic surgery to remove the stone, and ultimately effectively lift the obstruction. 3. bladder outlet obstructive disease: when the baby bladder neck contracture and other diseases, will also improve the hydronephrosis situation, for this situation can be used to indwelling urinary catheter or cystostomy to urinary drainage, in the full recovery of renal function and then surgical treatment. After the baby has hydronephrosis, it should not be delayed, it should go to the regular hospital for treatment, and actively deal with it in order to restore the kidney function.