1. Selection criteria of liver transplantation. At present, liver transplantation for hepatocellular carcinoma in China is mostly used as a complementary treatment for patients who cannot be surgically resected, cannot be treated with microwave ablation or TACE, and whose liver function cannot be tolerated. The selection of appropriate indications is the key to improve the efficacy of liver transplantation for hepatocellular carcinoma and to ensure the fair and effective utilization of the extremely valuable liver donor resources. Regarding the indications for liver transplantation, the Milan criteria are mainly used internationally, as well as the UCSF criteria and the Pittsburgh modified TNM criteria. (1) Milan criteria: proposed by Mazzaferro and others in Italy in 1996. In 1998, the United States Organ Allocation Network (UNOS) began to adopt the Milan criteria (plus MELD/PELD score, also known as UNOS criteria) as the main basis for screening liver transplant recipients for liver cancer. The Milan criteria have gradually become the most widely used liver transplantation screening criteria for liver cancer in the world. The advantages of the Milan criteria are that the efficacy is certain, the 5-year survival rate is ≥75%, the recurrence rate is <10%, and only the size and number of tumors need to be considered, which is convenient for clinical operation. However, the Milan criteria are too stringent, and many patients with liver cancer who could potentially be treated well with liver transplantation are denied access. Due to the shortage of donors, patients with liver cancer who originally met the Milan criteria were easily eliminated while waiting for a donor liver due to tumor growth beyond the criteria. Secondly, there is no significant difference in the overall survival rate between liver transplantation and liver resection for small hepatocellular carcinoma meeting the Milan criteria, except that the tumor-free survival rate of the former is significantly higher than that of the latter. In addition, the Milan criteria are difficult to apply to living donor liver transplantation and to the screening of liver transplant recipients after down-staging of intermediate to advanced liver cancer. (2) University of California, San Francisco (UCSF) criteria: In 2001, Yao et al. proposed the Milan criteria and expanded the indications for liver transplantation to a certain extent, including: the diameter of a single tumor does not exceed 6 or 5 cm; the number of multiple tumors ≤ 3, the maximum diameter ≤ 4 or 5 cm, and the total tumor diameter ≤ 8 cm; and there is no vascular or lymph node invasion. The UCSF criteria also expand the scope of indications of the Milan criteria without significantly reducing postoperative survival; therefore, in recent years, there has been an increase in the literature supporting the application of the UCSF criteria to screen liver transplant recipients for hepatocellular carcinoma, but there are also controversies; for example, the lymph node metastasis and tumor vascular invasion (especially microvascular invasion) proposed by the criteria are difficult to be diagnosed preoperatively. After thorough discussion by the panel, this guideline tends to recommend the UCSF criteria. (3) Pittsburgh modified TNM: In 2000, Marsh et al. proposed that only the presence of any one of the three criteria: large vessel invasion, lymph node involvement or distant metastasis as a contraindication to liver transplantation, but not the size, number and distribution of tumors as criteria for exclusion, thus significantly expanding the scope of liver transplantation for liver cancer, and may have nearly 50% of patients In recent years, there have been more and more studies supporting the UCSF criteria. However, this criterion also has significant drawbacks. For example, it is difficult to make an accurate preoperative assessment of microvascular or branch vessel invasion in liver segments, and many patients with hepatocellular carcinoma with a background of hepatitis may have inflammatory lymph node enlargement in the hilum and other areas, requiring intraoperative frozen sections for a definitive diagnosis. Second, due to the deepening conflict between liver supply and demand, although the expanded liver transplantation indication for liver cancer may allow some individual patients with intermediate to advanced liver cancer to potentially benefit from this, their overall survival rate is significantly reduced, and this reduces the availability of donor livers for patients with benign liver disease who may be able to achieve long-term survival. (4) Domestic standards: Nowadays, there is no unified standard in China, and several units and scholars have successively proposed different standards, including Hangzhou standard, Shanghai Fudan standard, Huaxi standard and Sanya consensus. The requirements for the absence of large vessel invasion, lymph node metastasis and extrahepatic metastasis are relatively consistent, but the requirements for the size and number of tumors are not the same. The above-mentioned domestic standards have expanded the scope of indications for liver transplantation for hepatocellular carcinoma, which can benefit more patients with hepatocellular carcinoma by liver transplantation and did not significantly reduce the cumulative survival rate and tumor-free survival rate after surgery, which may be more in line with the national conditions and actual situation of patients in China. However, a standardized multicenter collaborative study is needed to support and prove this, so as to obtain high-level evidence-based medical evidence to achieve recognition and uniformity. 2. Prevention of recurrence after liver transplantation. The common feature of the above-mentioned domestic and foreign liver cancer liver transplantation recipient selection criteria is that the tumor size is the main judgment indicator, which is more objective and easy to grasp, but the biological characteristics of liver cancer are not considered enough. It is generally believed that the biological behavior of the tumor is the most important factor in determining the patient's prognosis. Therefore, with the continuous development of molecular biology, some molecular markers that can better reflect the biological behavior of liver cancer and predict the prognosis of patients will be discovered, which may help to improve the current liver transplantation criteria for liver cancer and improve the overall survival rate. It is currently believed that appropriate drug therapy (including antiviral therapy as well as chemotherapy) can be administered after liver transplantation with the potential to reduce and delay liver cancer recurrence and improve survival, but further studies are needed to obtain sufficient evidence-based medical evidence.