Abstract: 160 one day old Avian broiler chickens were randomly divided into four groups, and fed the basal diet supplemented 0%、0.2%、0.4% and 0.8% Gln for 28 days. Six chickens in each group and total 24 were selected and slaughtered on the weekend till fourth week. The thymus and bursa of Fabricius were obtained, weighted and fixed by Bouin liquid, made into paraffin section, stained with HE, observed by microscope and photographed by micro-projector. Studied the effect of dietary Gln (Glutamine) supplementation on post embronic development of central lymphic organs in broiler chickens. The result:（1）Compared with the control group, there was a significant difference（P<0.05）among the thymus weight of experiment 3 of one and four-week age, that of experiment 2 of two and four-week age and the weight of bursa of Fabricius of experiment 2 of one, two and four-week age, and that of experiment 3 of four-week age. There was a most signifcant difference（P<0.01） between the weight of thymus of experiment 3 of two-week age and that of control group, the weight of bursa of Fabricius of experiment 3 of one and two-week age as well. （2）The thymic lobule of experiment group increased, the thymic cortex incrassated and the lymphocyte became coarctate, the portion of thymic medulla decreased and thymic corpuscle enlarged and increased. The lymph follicule in plica of bursa of Fabricius of experiment group added, in contrast, that of control group of four-week age was greatly decreased. The cortex of bursa of Fabricius incrassated with the lymphocyte in lymph follicule increased. The most obvious effect was showed on the experiment supplemented 0.8% Gln. The result shows that diet supplemented Gln could obviously boost the post emronic development of central lymphic organ in broiler chickens. In addition, Gln could retard the degenerating in central lympic organ, especially in bursa of Fabricius. At the point of tissue structure, Gln could promote the proliferation and differentiation of T and B lymphocyte, and the post embronic development of central lymphic organ, furthermore enhanced immune functions of organism by this means.