Abstract: Objective: To study the effect of soybean meal and corn yellow powder fermentation of Bacillus subtilis on immune function of mice.Methods: Low-, medium-and high-dosage group were fed with 0.334, 0.667 and 2 g/ (kg·d) soybean meal and corn yellow powder fermentation of Bacillus subtilis, respectively, equal volume of pure water as control group.30 days later, the following experiments were conducted that DNFB induced mouse delayed type hypersensitivity, mouse spleen lymphocyte transformation capacity induced by Con A, antibody forming spleen cells, serum hemolysin, carbon clearance ability, NK cell activity.Results: Soybean meal and corn yellow powder fermentation of Bacillus subtilis has significant impact (p < 0.05) on mouse carbon clearance ability, spleen lymphocyte transformation, serum hemolysin capacity, phagocytic index a and NK cell activity.However it had no significant effect on production of spleen cells formed by antibody (p > 0.05) . Conclusions: Soybean meal and corn yellow powder fermentation of Bacillus subtilis had effect on enhancing immunity.