Aimed to investigate the effect of water extract from Fuzhuan brick-tea on the immune functions of mice, one hundred and ninety mice were divided into 5 groups: control group, model group in which the mice were infected with Escherichia coli O157:H7, low dosage group, moderate dosage group and high dosage group in which mice were treated with low, moderate and high dosage of water extract from Fuzhuan brick-tea respectively for consecutive 10 d. Results demonstrated that there is remarkable difference in the phagocytic index, the serum hemolysin titers and the number of CD4+ and CD8+ T-lymphocytes in intestinal mucosa between control and model group. Compared with model group, the thymus index in moderate group and serum hemolysin titers in high dosage group are significantly higher (P＜0.01) ; the serum hemolysin titers in moderate group and the thymus index in high dosage group and the number of CD4+ and CD8+ T-lymphocytes in intestinal mucosa in moderate and high dosage groups increased significantly (P＜0.05); the phagocytic index increased significantly in low (P＜0.05), moderate and high (P＜0.01) dosage groups.