To investigate the immunomodulatory effects of the three non-digestible oligosaccharides, fructooligofructose, xylooligosaccharide and galactooligosaccharide, and their combinations on mice,140 BALB/c female mice were randomly divided into 7 groups in this experiment, including blank control group, FOS group, XOS group and GOS group, XOS and GOS group, XOS and FOS group, FOS and GOS group. Each group was intragastrically administered at a dose of 400 mg/kg once a day for 15 days. The immunomodulatory effects of different non-digested oligosaccharides and their combinations on mice were evaluated by measuring immune organ index, macrophage phagocytosis, serum hemolysin level, DTH delayed type hypersensitivity, and spleen lymphocyte proliferation. The results showed that the immunological indexes of the single oligosaccharide-administered group and the combined oligosaccharide-administered group were significantly higher (P<0.05 or P<0.01) than the control group. The immune index of combined oligosaccharide gavage group rats was higher than the single oligosaccharide gavage group, and the combination of xylooligosaccharide and galacto-oligosaccharide (11.5) was the best. The above results indicated that non-digestible oligosaccharides could enhance the immune response ability of mice and the combination of them had better effect.