Milan standard: the most widely used standard in the world: single tumor diameter ≤ 5 cm; multiple tumors less than 3, maximum diameter ≤ 3 cm. Its advantages are: the efficacy is certain, the 5-year survival rate is above 75%, recurrence rate < 10%; only the size and number of tumors need to be considered, which is convenient for clinical operation. Disadvantages: it is too strict, and some patients who may be cured are excluded; the biological characteristics of tumor are not considered enough, such as vascular invasion, lymphatic metastasis, tumor grading and tumor markers.