Abstract: In order to study the effect of heat-killed Mycobacterium phlei as an oral non-specific immunomodulator on Newcastle disease（ND） and Avian influenza H9 subtype（AI-H9） vaccine, A total of 150 one-day-old chicks were divided into 5 groups using the completely randomized method in this experiment,including blank control group,test groups（with high,medium and low doses of Mycobacterium phlei）,and vaccine control group. The test groups were perfused artificially with heat-killed Mycobacterium phlei on 3 days of age for 7 consecutive days. Except for the blank control group,the other groups were injected subcutaneously with the combined inactivated vaccine of Newcastle disease and Avian influenza（H9 subtype） on 7 days old. On 7,14,21,28,35 days post immunization,the average body weights and IgA contents in sera and small intestinal mucus,peripheral lymphocyte proliferation,HI antibody levels in chickens were determined respectively. The results showed that on 14,21,28,35 days post immunization,IgA contents in small intestinal mucus,and OD₅₇₀ values of peripheral lymphocytes were significantly higher than those in blank control group and vaccine control group（P＜0.05）. On 21,28,35 days post immunization,the body weights and serum IgA contents were significantly higher than those in blank control group and vaccine control group（P＜0.05）. The ND and AI-H9 antibody levels in the test group were not significantly different from those in blank control group and vaccine control group（P＞0.05）. The results suggested that oral heat-killed Mycobacterium phlei could significantly enhance the cellular immune response,significantly increase serum and small intestinal mucus IgA secretion,promote the proliferation of peripheral lymphocytes,and increase the average weights of chickens.