When the renal cyst is 30mm*27mm, you can generally give conservative treatment, pay attention to regular follow-up, and if necessary, surgical treatment. 1. Conservative treatment: If the renal cyst develops rapidly, exceeds 4cm in value, and presses the surrounding tissues and organs, or causes urinary tract obstruction, it can be treated by cystic fluid aspiration or intracystic injection of sclerosing agent, etc. If infection occurs, anti-infective treatment and cystocentesis and drainage are needed. If the renal cyst is infected, anti-infection treatment and cyst puncture drainage are needed. 2. Regular follow-up: If the renal cyst has reached 30mm*27mm, but there is no obvious clinical symptom such as pain in the kidney area, hematuria, etc., and the renal function test is normal, you can go to the hospital for regular review in 6~12 months. 3. Surgical treatment: cystectomy or even nephrectomy should be considered for patients with huge cysts with volume >500ml, malignant tendency or recurrence after puncture. If you find that the cyst has reached 30mm*27mm, it is recommended to consult regular hospitals and follow the doctor’s instructions for examination and treatment to avoid delaying the condition.