Children with hydronephrosis should pay attention to the following two aspects: First, once found, children with hydronephrosis should go to the pediatric department of the hospital as soon as possible, to perform urological ultrasound or CT examination of the urinary system to clarify whether the cause of hydronephrosis is stones, congenital malformation of the ureter, or chronic inflammation resulting in ureteral stenosis, etc. Only after clarifying the cause can the corresponding treatment be carried out in a timely manner, so as to lift the obstruction and relieve the situation of hydronephrosis; Second, after clarifying the diagnosis of hydronephrosis, we should go to the pediatric department for regular review, blood sampling to check the kidney function and urological ultrasound to dynamically understand the changes of hydronephrosis.