Abstract: Objective To establish mouse allergic asthma model and observe the effect of bacterial lysates (OM-85BV) on airway inflammation. Methods Forty-eight 4 to 6 weeks healthy male BALB/c mice were used as research subjects and randomly divided into six groups, a: control group; b: OM-85BV contral group; c: allergic asthma model; d: dexamethasone group (Dex group); e: OM-85BV A group; f: OM-85BV B group (the intervention time was prolonged 10 days than group e). BALB/c mice were sensitized and challenged with ovalbumin (OVA). Mice in groups c, d, e and f were intraperitoneally administered with antigen (OVA)-Al(OH)3 on days 1, 8 and 15, others were administered by PBS. From the 17th day to the 26th day, Mice in group f were treated with OM-85BV and others were treated with normal saline. In the next days, mice in groups c, d, e and f were intranasal given OVA for 5 consecutive days. Additionally, mice in groups b, e and f were treated with OM-85BV before challenge, while mice in the group d were administered by Dex, others were treated with normal saline at the same dose. Twenty four hours after the last intranasal administration, mice were anesthetized and dissected. Lungs were lavaged with PBS and bronchoalveolar lavage fluid (BALF) was obtained. The total inflammatory cells and eosinophils in BALF were counted. The total IgE levels of blood serum and IFN-γ/IL-4 levels of lavage were detected. The removed parts of lung tissue were collected for histological examination. Results Compared with groups a and b, lung tissue biopsies by HE staining from the asthma group showed obvious airway inflammation. The situation of groups d and f was significantly improved than group c, while the differences between groups e and c were not evident. Total cells and the number of eosinophils in BALF of group c (90.3±13.94×104/ml) were significantly higher than that in groups a and b. Compared with the control group, levels of IL-4 in BALF (119.03±19.92 pg/ml) and IgE in serum (15.86±1.97 ng/ml) increased and levels of IFN-γ in BALF (90.50±13.51 pg/ml) reduced significantly. The corresponding levels of groups d, e and f were significantly improved than group c (P<0.01). Conclusions Administered by OM-85BV helps regulate the balance between Th1/Th2 in asthmatic mice, reduce airway inflammation, and prevent the occurrence and development of airway inflammation