The activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and concentrations of malondialdehyde (MAD) in serum, spleen and bursa of Fabricius and the concentrations of Immunoglobulin G (IgG) , Immunoglobulin A (IgA), Immunoglobulin M (IgM) and HI antibody titer to Newcastle Disease in serum were detected in chickens with different levels sub-chronic aluminum (Al) intoxication produced by continuous peritoneal injection of various gradient aluminum trichloride (AlCl3). The results showed that the concentrations of MDA in chickens were higher and other indexes were lower in the experimental groups than in the control group. There was significantly different (P<;0.05 or P<;0.01) between groups, dose-effect relationship between with AlCl3. The results indicate that Al exposure inhibits the antioxidative activity and humoral immune function in chickens.