What should we do if hydronephrosis occurs. The specific strategy should be based on the specific cause of hydronephrosis, the degree of hydronephrosis and the combined symptoms, as well as the patient’s wishes, to analyze the specific causes and develop a specific plan. If the hydronephrosis is temporary, such as holding urine will cause a transient, relatively mild hydronephrosis, and ureteral stones will also cause a mild hydronephrosis in the short term, and when these causes are removed, the hydronephrosis will also be relieved, so there is no need to deal with hydronephrosis alone. Primary hydronephrosis, most commonly pelvic ureteric junction stenosis, often develops slowly and often has no specific symptoms, so it can be closely observed and actively treated when the hydronephrosis progresses significantly, or when the hydronephrosis is heavy and combined with related comorbidities. Secondary hydronephrosis is often caused by inflammation, stones, tumors, or injury. The cause of the hydronephrosis, the specific location of the obstruction, and the degree of obstruction need to be clarified in time, and depending on the situation, surgery can be performed to remove the cause or reconstructive surgery of the upper urinary tract to restore the smoothness of the urinary tract if necessary. In addition to some reconstructive surgery, placement of ureteral stent or pyelostomy is also an effective solution to relieve hydronephrosis, which needs to be handled carefully according to the specific situation.