Severe hydronephrosis with 20% of renal function left, the first step is to actively discharge the hydronephrosis, if the hydronephrosis can not be effectively corrected, then resection can be considered, or non-resection can be considered to take the pyeloplasty for correction. Clinical treatment of hydronephrosis with very poor renal function is still divided. Some of them think that nephrectomy should be performed, some of them think that percutaneous nephrostomy drainage test can be performed first, and then pyeloplasty or nephrectomy can be performed; and a few of them think that pyeloplasty should be performed directly, and then nephrectomy should be performed if the renal function is still declined after the operation. Hydrocele first perform pyeloplasty, it is possible to improve the patient’s renal function, so that the renal function is better, renal function less than 10% of the kidney renal function is considered to be non-functional kidneys, while 20% of the renal function of the kidney still have the possibility of use. Specifically which surgical program to perform, but also need to combine the local medical institutions and the patient’s clinical specific analysis. It is recommended that patients go to regular hospitals in time, and under the guidance of doctors, do not delay, so as not to cause the deterioration of the condition.