To explore the anti-tumor effects of Gucao Shengji Decoction on H22 tumor-bearing mice and its immunomodulatory mechanism on the body.Methods:In this study，an H22 tumor-bearing model was established in mice.Mice were randomly divided into a blank group，a model group，a positive drug group，and low-and high-dose Gucao Shengji Decoction groups.The mice were orally administered the corresponding drugs for 7 days.The body weight growth rate，tumor inhibition rate，thymus index，and spleen index of the mice in each group were calculated.The tumor tissues and cell morphology were observed by hematoxylin-eosin(HE) staining.Enzyme-linked immunosorbent assay(ELISA) was used to detect the levels of gamma interferon(IFN-γ)，tumor necrosis factor-α(TNF-α)，interleukin-2(IL-2)，Fas，Fas ligand，aspartate aminotransferase(AST)，and alanine aminotransferase(ALT) in the mouse serum.Real-time fluorescence-based quantitative PCR was used to measure the relative expression levels of Bax and Bcl-2 mRNA in the tumor tissues of the mice.Results:Gucao Shengji Decoction promoted the growth of H22 tumor-bearing mice，inhibited the growth of solid tumors，and induced tumor apoptosis and necrosis.Additionally，it increased the thymus index，decreased the spleen index of the mice，significantly increased the levels of IFN-γ，TNF-α，and IL-2 in the mouse serum，decreased the levels of Fas，Fas ligand，AST，and ALT(all P<0.01)，upregulated the expression of Bax mRNA，and downregulated the expression of Bcl-2 mRNA in the tumor tissues.Conclusion:Gucao Shengji Decoction has significant anti-liver tumor effects in vivo，which can inhibit tumor growth，promote tumor cell apoptosis，and modulate the body's immune response.