Severe hydronephrosis is often caused by long-term urinary tract obstruction. In case of unilateral severe hydronephrosis, it often causes thinning of the renal cortex and loss of renal function, at which time nephrectomy can be performed. Since the other kidney is still alive, it can be completely compensated and the organism will not be affected much. If the kidneys are severely fluidized for various reasons and the kidney function is lost bilaterally, the patient is usually in a state of kidney failure and needs urgent dialysis treatment. The maintenance of patients’ lives can only be ensured through dialysis or kidney transplantation. For the occurrence of hydronephrosis, timely examination and treatment can prevent the occurrence of severe hydronephrosis.