Abstract: A total of 144 one day-old AA Broilers were randomly divided into 2 groups, each group included 72 chickens. The control group was fed on the basal diet for 42 days, and that of experiment group supplemented 1 % pine-needle powder and1% Mai-Fan rock. Six chickens in each group were selected and slaughtered at 7, 14, 21, 28, 35, 42 days respectively, the thymuses，bursa of Fabricius and spleens were obtained, weighted, fixed in Bouin liquid and made into paraffin section. The results were as follows: Compared with control group, the weight and the relative weight of thymuses, bursas of Fabricius and spleens of experiment group increased significantly(P＜0.05) or extremely significantly(P＜0.01). In experiment group, the cortex of thymic lobule, bursa nodule and Periarterial Lymphatic Sheaths thicken obviously; the volume of bursa nodule, splenic nodule and ellipsoid augmented, and the germinal center of splenic nodule were obvious; the thymic corpuscle increased; the plica of bursas of Fabricius developed well and the degenerating of it retarded. The result shows that the pine-needle powder and Mai-Fan rock compound additives could boost the early development of thymus and bursas of Fabricius, retard the degenerating of bursas of Fabricius and promote the immune response of spleen.