The changes of T–lymphocytes subsets around peripheral blood were detected employing flow cytometer and the content of serum IL–2 and IFN–γ were determined using ELISA method to judge the damage of cellular immune function induced by AFB1 exposure based on one hundred male avian broilers fed with a control diet and three AFB1 diets (with 0.15, 0.3, 0.6 mg/kg amount of AFB1 addition, respectively, marked with AFB1Ⅰ,Ⅱ, Ⅲ in turn)for 21-day. The results showed that the percentage of CD3+, CD3+CD4+ and CD3+CD8+ T lymphocytes were decreased from 7 to 21 days of age (P<0.05 or P<0.01)in AFB1Ⅱ and AFB1 Ⅲ groups, and the contents of serum IL–2 at 14 days of age and IFN–γ at 7 days of age were decreased in AFB1 Ⅰ group (P<0.05). The results indicated that the cellular immune function was declined by consumption the diet of AFB1 contamination.