Severe hydronephrosis is more serious, the renal parenchyma is significantly damaged and atrophied causing renal hypertension or combined with serious infections, and the affected kidney can be removed when the opposite side of the kidney functions normally. Hydronephrosis refers to the obstruction of urine drainage from the renal pelvis, the accumulation of increased intrarenal pressure, dilatation of the renal pelvis and calyces, atrophy of the renal parenchyma, and loss of function. Urinary tract obstruction may have different clinical manifestations depending on the etiology, site of obstruction, degree and duration. Severe hydronephrosis with significant destruction of renal parenchyma, atrophy, causing renal hypertension or combined with severe infection, and severe loss of renal function while the contralateral side has normal renal function may result in resection of the affected kidney because it is necessary to ensure that the patient’s contralateral side can be compensated for after the removal of one side of the kidney. For the same disease, the treatment method is different due to different physical conditions of patients and the disease is in different stages, and should be standardized under the guidance of doctors.