Oxysophocarpine sensitized the Lag‐3 immunotherapy effect of CD8+ T cells against HCC in vivo and in vitro by decreasing Fibrinogen‐like protein 1 (FGL1) expression through downregulating IL‐6‐mediated JAK2/STAT3 signaling, whereas Oxysophocarpine treatment had a little effect of CD8+ T cells cytotoxicity function against HCC with PD‐1, Tim‐3, or TIGIT blockade. Here, FGL1 is linked to hepatocellular carcinoma.