40 healthy one-day-old chickens were selected in this experiment，which were randomly divided into four groups，so each group were 10，the group I was control group，the three experimental groups（II，III and IV group）were subcutaneous injected with Astraglus polysacchride. They were fed in the same conditions. In the fifth day，each chicken of II，III and IV group was given 0.1mg，0.3mg and 0.5mg of APS by subcutaneous injection， respectively. Physiological saline was injected in control group，which was injected once a day for three successive days. Lasota vaccine of ND was given by eye and nasal droping at 7-day-old and 21-day-old，respectively. The dynamic variation of serum HI antibody was determined by β-micromethod. The results showed that Aps played a promoting role in the immune effects of ND. There were distinct differences between experiment groups and the control group. While the best dose of Astragalus polysaccharides was 0.5 mg per each. It could conclude that a certain dose of APS can significantly enhance the effect of Newcastle disease immunization