To determine the effect of TGF-β1 on the expression of PD-1 and CTLA-4 on T cells and its effect on the development of HCC in vivo. We subcutaneously transplanted H22 cells, a mouse-derived HCC cell line, to KM mice, and injected mouse-derived TGF-β1 (70ng/mL, 280ng/mL) or normal saline via tail vein three days after inoculation, once a day with the dosage of 5mL/kg. The gene discussed is PDCD1; the disease is hepatocellular carcinoma.