Separation of the renal collecting system by 23mm is considered as severe hydronephrosis, which may affect the kidneys over time and even lead to renal insufficiency or acute kidney injury. Hydronephrosis is the enlargement of renal pelvis and calyces caused by urinary tract obstruction. Urinary tract obstruction can occur in any part of the urinary tract, either unilateral or bilateral, and the degree of obstruction can be complete or incomplete, which will lead to hydronephrosis after a period of time, and most of the hydronephrosis will be accompanied by stones, and the hydronephrosis will disappear after the stones are treated. Separation of the renal collecting system by 23mm is considered as severe hydronephrosis. Long-term hydronephrosis will compress other tissues of the kidney and lead to kidney damage, even leading to renal insufficiency or acute kidney injury. It should be treated immediately, and drugs can be chosen to expel the stones during the treatment. In daily life, you should pay attention to drink more water and exercise, it is best to drink more pure water, eat less food with high oxalic acid content, and pay attention to a light diet. It is recommended that the patient timely hospital consultation, according to the doctor’s recommendations for treatment, do not blindly treat yourself, so as not to delay the condition.