Duplication of the renal pelvis is a congenital malformation of the urinary system related to the differentiation of the mesonephric ducts during embryonic development. A renal duplication malformation may occur when the mesonephric duct branches prematurely during embryonic development. Later in life, double renal pelvis and double ureter can be detected by imaging. Different developmental conditions cause different clinical signs. A large proportion of the population is born completely normal and does not affect the normal function of the urinary system; some of them are accompanied by urinary symptoms and can be treated surgically if necessary. The discovery of double renal pelvis needs further investigation, can be done pyeloureterography, or CT urography, to determine the specific excretory function, if there is a suspicion of infection can be done urine routine as well as renal function tests. If you find abnormalities in the urinary system, you should consult a doctor in time to get a clear diagnosis and standardized treatment, and strive for early recovery.