The kidney fluid usually cannot be discharged by itself because there is no fluid in the kidney under normal circumstances. Any fluid indicates the presence of primary diseases, such as urinary tract infection, urinary tract stone, urinary tract tumor, etc. If the fluid is caused by infection, it is usually combined with urinary frequency, urinary urgency, urinary pain, hematuria, lumbar pain and general discomfort such as chills and fever, which requires antibiotic treatment for 10-14 days, and the fluid can disappear by itself when the infection is controlled and stable. In case of small stones caused by stones, the fluid can disappear by itself through drinking more water, urinating regularly and doing more vigorous exercises. In case of larger stones, extracorporeal shock wave lithotripsy or surgical stone extraction is required to cure the effusion after the stones are discharged. If the fluid is caused by tumor compression, active treatment of tumor is needed. Advanced tumor can be treated by pelvic fistula to relieve the pressure of fluid on the kidney.