The purpose of this study is to assess the difference of safety and efficacy about PD-1 Antibody and Lenvatinib Plus transcatheter arterial chemoembolization (TACE) on downstaging hepatocellular carcinoma with BCLC B/C.

Inclusion Criteria:

1. Age ≥18 years old and ≤75 years old;
2. Clinically diagnosed as hepatocellular carcinoma, stage B/C of BCLC;
3. No history of severe arrhythmia or heart failure;
4. No history of severe ventilation dysfunction or severe pulmonary infection;
5. No acute or chronic renal failure, the creatinine clearance rate was >40 mL/min;
6. Liver function Child A;
7. Blood routine: absolute neutrophils count ≥1.5×10^9/L, Hb≥8.5g/L, PLT≥75×10^9/L;
8. Coagulation function: INR≤2.3;
9. ECOG score <2;
10. No local or systemic treatment, such as TACE, RFA, targeted drugs, traditional Chinese medicine, etc., before enrollment;
11. Expected survival ≥12 weeks;
12. At least one lesion can be measured and evaluated by CT/MRI according to RECIST 1.1 criteria;
13. Understand and sign the informed consent.

Exclusion Criteria:

1. Pregnant or lactating women;
2. Patients with other malignant tumors;
3. patients with complicated mental illness;
4. patients who have participated in other clinical trials in the last three months;
5. known or suspected allergy to any drug related to the study;
6. Patients with positive immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS)
7. Patients treated with other targeted drugs, PD-L1 antibody and other immunotherapy or FOLFOX systemic chemotherapy after inclusion;
8. Patients with ≥1 + proteinuria indicated by urine routine will receive 24-hour urine protein detection, and patients with ≥1g 24-hour urine protein will not be included in the group.
9. Active autoimmune diseases that require systemic treatment (use of disease-alleviating agents, such as corticosteroids or immunosuppressants)
10. Patients with uncontrolled hepatitis B/C infection
11. Other conditions that the researcher considers not suitable for inclusion in this study