Urinary tract obstruction is one of the common causes of renal failure. As long as it is discovered in time and the obstruction is relieved as soon as possible, most renal failure can be improved. The urinary system is a pipeline system. Only when the lumen is unobstructed can the normal function of the urinary system be maintained. Obstruction of the lumen affects the secretion and excretion of urine. Many lesions inside and outside the urinary system can cause lumen obstruction. The obstruction may be located in the kidney, the ureteropelvic junction, the ureter itself, the ureterovesical junction, the bladder neck or the urethra. The closer the obstruction is to the kidney, the faster the hydronephrosis occurs. Urinary system obstruction occupies an important position in pediatric urinary system lesions. Many lesions and obstructions in the urinary system are often causal. For example, infection and stones can cause obstruction. Obstruction of different reasons is conducive to the occurrence of infection and stones, which aggravates the complexity of the lesion and the damage to the kidney. Therefore, when there is a urinary system disease, it is necessary to pay attention to whether there is an obstruction problem and conduct corresponding examinations to relieve the obstruction in time, drain urine, and protect renal function.