A parapelvic cyst is a specific type of renal cyst that is largely encapsulated by the renal parenchyma, with only a small portion of the renal hilum being visible. Larger parapelvic cysts may compress the renal parenchyma or compress the urinary duct system leading to hydronephrosis and impairment of renal function. Simple renal cysts can usually be treated with puncture and drainage or open window surgery. Because there are large blood vessels in the kidney and urinary ducts such as the renal pelvis entering and leaving the kidney at the renal hilum, the external window surgery to reveal the parapelvic cyst has a large incision, and in addition, it may cause serious complications by damaging the large blood vessels or the renal pelvis. We use percutaneous nephrological technique to enter the kidney directly and establish a channel between the cyst and the urinary ducts from inside, avoiding the large blood vessels of the kidney, reducing the risk of the operation and achieving better results.