Abstract: Objective: Taking gonad saponins from female of Apostichopus japonicus (AGS) as the research object to explore its immune-enhancing activity. Methods: The immunoregulatory activity of AGS in vitro was studied by measuring the phagocytosis and cytokines of macrophages. Thereafter the immunoregulatory activity of AGS in immunocompromised mice was analyzed by measuring thymus and spleen index, carbon clearance index and phagocytic index, proliferation activity of peritoneal macrophages, spleen cells, NK cell activity, T lymphocyte subsets level and serum cytokines of mice. Results: In vitro experiments showed that AGS could improve the phagocytic ability of macrophages and enhance the secretion of TNF-α, IL-6 and IFN-γ, and each group was significantly different from the normal group (P<0.05). In vivo experiments showed that compared with model group, AGS in middle dose group and high dose group could significantly increase thymus and spleen index, carbon clearance index and phagocytosis index (P<0.05), significantly enhance the proliferation activity of peritoneal macrophages and spleen cells (P<0.05), significantly enhance the activity of NK cells (P<0.05), significantly increase the level of CD4⁺/CD8⁺ (P<0.05), and significantly promote the secretion of TNF-α, IL-6, and IFN-γ (P<0.05). Conclusion: AGS exhibits immune-enhancing activity both in vitro and in vivo.