Abstract: Abstracts: The purpose of the experiment was to investigate the immune effects of different dosages of compound probiotics, astragalus polysaccharides, compound probiotics and astragalus polysaccharides on the immune organ index and Newcastle disease and avian influenza in chickens. 360 Ai Weiyin broilers were allocated into six groups. The six treatments was: Ⅰ basic diet; Ⅱ basic diet 0.2% compound probiotics, Ⅲ basic diet 0.4% compound probiotics, Ⅳ basic diet 0.6% compound probiotics; Ⅴ basic diet 0.3% astragalus polysaccharide in the three days before per week; Ⅵ basic diet 0.4% compound microbial ecological agents 0.3% astragalus polysaccharide in the earlier three days of each week. The experiment lasted 42 days. The results showed that group II, III, IV could improve the immune organ index and antibody level of Newcastle disease and avian influenza. Specifically, group III and IV had significant effect, and effect of group II was significant at the 42 age in days (P<0.05). Group III was the best among them. Effect of group V was also significant at the 42 age in days (P<0.05). Compared with the control group, group VI could significantly improve the immune function of broilers during the test process (P<0.05). Compared with group Ⅱ, Ⅲ, Ⅳ, the immune function of group VI was significantly greater than that of group II and IV (P<0.05), but greater than that of group III, the difference was not significant (P>0.05). Compared with group Ⅴ, group VI had remarkable effect (P<0.05). Both micro ecological preparation (Yi Duo Bao) and astragalus polysaccharide could improve the immune function of broilers, and there is synergetic action between them, combined use has better effect than separate use.