Left renal cyst with uneven echogenicity of the left renal parenchyma is considered a possible case of hydronephrosis. The treatment of renal cystic fluid mainly depends on the severity of the fluid, mild need to be evaluated before deciding whether treatment is needed. For severe hydronephrosis, surgical treatment is usually the mainstay. Hydronephrosis with renal pelvis separation of 4~9mm is generally considered to be mild and usually does not require treatment. Renal pelvis separation >14mm, usually considered as severe hydronephrosis, if the patient has severe hydronephrosis for a longer period of time, it may have some impact on renal function, the treatment is mainly surgical treatment, including puncture to extract the cystic fluid and hit the solidifying agent, decapitation and decompression, and nephrocystectomy. After the treatment of renal cysts, the degree of fluid accumulation can usually be improved. Left renal cyst left renal parenchymal echogenicity uneven patients, it is recommended to timely regular hospital consultation, clear diagnosis and treatment, targeted treatment.