The left parapelvic cyst is usually an acquired renal cyst caused by repeated urinary tract infections. Once a renal cyst is formed, it will not disappear on its own; small renal cysts can be observed regularly; large renal cysts are usually larger than 5 cm in diameter, and renal cyst puncture and drainage or renal cyst depanalization and decompression are feasible. Because renal cysts, if not treated in time, will compress the normal kidney tissue, affect the blood supply to the kidneys and cause abnormal kidney function, and renal cysts are a cystic cavity, the long-term existence of which will cause complicated urinary tract infections. Once patients who have kidney cysts are recommended to review blood routine, urine routine, ion kidney function and urinary tract ultrasound every 3-6 months to prevent irreversible consequences due to the progress of the disease.