Abstract: Objective To explore the effects and possible mechanisms of oral BCG in treating anaphylactic-type I reaction. Methods Ovalbumin sensitized mice were treated with BCG from low-dose to high-dose by oral application and the emergence time, severity of asthma symptoms ，also the effects no the antibody titre of specific IgE and IgG and the mRNA of IL-1,2,10,12 with different doses were recorded. Results Oral BCG range from 0.5mg/kg to 2.0mg/kg can reduce the frequency of nose scraping in allergic mice in a standard times and delay the emergence time of asthma symptoms, reduce the air way resistance and the generation of the antibody titre of specific IgE, and regulate the mRNA expression of cytokins. Conclusions Oral BCG is valid on treatment of allergic asthmatic mouse model.The mechanism of induced tolerance immune were difference with the specific antigen and BCG.