The objective of this study was to compare the effects of different dietary levels of Astragalus polysaccharides (APS) on immune function and intestinal flora in laying hens. A total of 1 440 380-day-old healthy Hyline laying hens with similar productive performance were randomly allocated to six treatments with four replicates each and sixty hens in each replicate, and fed the corn-soybean meal based diets with 0 (group Ⅰ, control group), 50 (group Ⅱ), 100 （group Ⅲ）, 150 （group Ⅳ）, 200 （group Ⅴ）, 250 mg/kg （group Ⅵ） APS, respectively. The experiment lasted for eight weeks. The results showed as follows: 1) different levels of dietary APS could increase spleen coefficient, groups Ⅱ, Ⅲ, Ⅳ, andⅤ were significantly higher than the control group (P<0.05). About the number of lymph nodules of cecal tonsil and the length of intestinal villi, groups Ⅱ, Ⅲ, Ⅳ, Ⅴ and Ⅵ were higher than the control group, but they were not significantly different (P>0.05). 2) E. coil quantity in group Ⅳ was significantly lower than that in the control group (P<0.01), and there was significant difference between group Ⅲ and the control group (P>0.05); lactic acid bacteria quantity in group Ⅲ was significantly higher than that in group Ⅵ (P<0.01) and in group Ⅳ (P<0.05), but there was no significant difference compared with the control group (P>0.05); about Bifidobacteria quantity, there was a significant difference between group Ⅲ and group Ⅵ (P<0.01), but it was not significantly different among group Ⅲ, group Ⅵ and the control group (P>0.05). In conclusion, the suitable level of dietary APS is 100 mg/kg.［Chinese Journal of Animal Nutrition，2011，23（3）：447-451］