Background: To determine the antitumor effects and its mechanism of n-butanol fraction from aril of Torreya grandis (BFAT) on H22mice models of liver cancer. Materials and Methods: Sixty ICR male mice were used to establish H22mice models of liver cancer and then randomly divided into six groups, the normal control group, the model control group, the positive group (cyclophosphamide [CTX]), the BFAT-treated group (high, 4 g/kg, medium, 2 g/kg, and low, 1 g/kg). The animals were sacrificed 15 days after oral administration, and tumors were taken out for the tumor weights and antitumor rates, while thymus and spleen were taken for thymus index and spleen index. Blood in eyeball was collected for the determination of aspartate aminotransferase (AST), alanine aminotransferase (ALT), albumin (Alb), malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase enzyme (GSH-Px), tumor necrosis factor-α (TNF-α), interleukin-2 (IL-2), transforming growth factor-β1 (TGF-β1), and IL-10 in serum. Sections of tumor tissue were prepared, and morphological changes in tumor tissue cells were observed using hematoxylin and eosin staining technique. Results: Compared with the model control group, the tumor inhibition rate of the high-dose administered group is 60.15%, which is quite closed to the effect of CTX. Moreover, the tumor weight is decreased, the indexes of spleen, thymus were increased significantly. Furthermore, the administration of BFAT significantly enhanced the activities of TNF-α, IL-2, SOD, and GSH-Px and reduced the levels of AST, ALT, MDA, Alb, TGF-β1, and IL-10 (P < 0.01). Conclusions: The results demonstrated that n-butanol fraction from aril of T. grandis showed out antitumor activity without obviously liver damage through potentiating immunologic function and antioxidant activity of tumor-bearing mice and which may become one potential as anticancer drug alternatives or supplements.