The clinical treatment of hydronephrosis should first be determined by urography to determine whether there is hydronephrosis, and then by urine protein, urinary ultrasound and renal function tests to determine the cause of hydronephrosis and the location of the lesion, and then to determine the severity of hydronephrosis, whether there is infection, and the damage to renal function, and finally to determine the further treatment plan. In clinical practice, the treatment of mild hydronephrosis is mostly conservative, mainly because the obstruction has not yet caused serious irreversible kidney damage. Usually, the cause of hydronephrosis should be removed first, and the hydronephrosis should be discharged from the body through the use of water-reducing drugs. If the cause of the obstruction can be identified, the obstruction should be removed through medication or surgery, such as urinary stones or kidney stones. Especially if the hydronephrosis keeps worsening and induces obvious clinical symptoms, such as oliguria and anuria, and the kidney function keeps decreasing, then surgery should be performed as soon as possible to relieve the hydronephrosis and avoid its further damage to the kidney function. If the patient has severe renal function impairment and the etiological inhibition of hydronephrosis has not been removed, then nephrostomy surgery may be required to deal with it. But before that, drainage should be performed to avoid the increase of kidney damage, and the infection can be controlled at the same time. When the infection is under control then surgery can be performed. For life-threatening conditions, nephrectomy may be required. To sum up, most of the hydronephrosis need to remove the cause of the disease, active symptomatic treatment, and a few patients with mild cases can be dynamically observed for regular follow-up.