Objective: To investigate the effect of intratracheally administered BCG DNA on a murine model of asthma. Methods: BALB/C mice were divided into 4 groups: normal control group, asthma model group, BCG DNA administered before OVA sensitization group, BCG DNA administered after OVA challenge group. The asthma models were developed by immunizing BALB/C mice with OVA. A total of 100 μg BCG DNA was intratracheally administered before OVA sensitization and after OVA challenge. WBC count and eosinophil percentage (EOS%) in bronchoalveolar lavage fluid (BALF) were measured. Changes of IL 4 , IL 5,IL 12, IFN γ in BALF were determined by ELISA. Pulmonary inflammation was observed on normal pathological slides and the proliferation and mucus secretion of goblet cells stained by AB PAS were also observed. Results: IL 4 , IL 5,IL 12, IFN γ in BALF of normal control group were(32.3±5.7)pg/ml,(15.6±3.9)pg/ml,(80±8.5)pg/ml,(153.2±9.4)pg/ml respectively. IL 4,IL 5 in BALF of asthma model group increased to (299±15.6)pg/ml and (206.7±9.3)pg/ml, while IL 12 and IFN γ decreased to (20.4±4.1)pg/ml and (51.6±5.5) pg/ml respectively. BCG DNA administered intratracheally before OVA sensitization and after OVA challenge significantly increased IL 12 [(71.6±8.3)pg/ml,(67.8±8.1pg/ml)] and IFN γ [(119.0±11.3)pg/ml,(114.7±10.1)pg/ml] in the BALF. Meanwhile, BCG DNA decreased IL 4 [(82.1±6.1)pg/ml,(86.3±5.9)pg/ml] and IL 5 [(32.3±4.6)pg/ml,(37.4±5.3)pg/ml]. Eosinophil level in BALF was inhibited and the pulmonary inflammation was dramatically relieved compared to asthma model group. Conclusion: Intratracheally administered BCG DNA can induce IL 12 and IFN γ secretion,inhibit Th2 response which can relieve allergic airway inflammation and provide a new way in the treatment and prevention of asthma. Methods: To investigate the effect of intratracheal administration of BCG DNA on a murine model of asthma. Methods: BALB / C mice were divided into 4 groups: normal control group, asthma model group, BCG DNA administered before OVA sensitization group, BCG DNA administered after OVA challenge group. The asthma models were developed by immunizing BALB / C mice with OVA. A total of 100 μg BCG DNA was intratracheally administered before OVA sensitization and after OVA challenge. WBC count and eosinophil percentage (EOS%) in bronchoalveolar lavage fluid BALF) were measured. Changes in IL 4, IL 5, IL 12, IFN γ in BALF were determined by ELISA. Pulmonary inflammation was observed on normal pathological slides and the proliferation and mucus secretion of goblet cells stained by AB PAS were also observed. Results: IL4, IL5, IL12, IFNγin BALF of normal control group were (32.3 ± 5.7) pg / ml, (15.6 ± 3.9) pg / ml, (80 ± 8.5) pg / ml, 9.4) pg / ml respectively. IL 4, IL 5 in BALF of asthm While model group increased to (299 ± 15.6) pg / ml and (206.7 ± 9.3) pg / ml respectively, while IL12 and IFNγ decreased to (20.4 ± 4.1) pg / ml and (51.6 ± 5.5) pg / ml respectively. BCG DNA administered intratracheally before OVA sensitization and after OVA challenge significantly increased IL 12 [(71.6 ± 8.3) pg / ml, (67.8 ± 8.1 pg / ml)] and IFNγ [(119.0 ± 11.3) pg / 10.11 pg / ml] in the BALF. Meanwhile, BCG DNA decreased IL4 [(82.1 ± 6.1) pg / ml, (86.3 ± 5.9) pg / ml] and IL5 [(32.3 ± 4.6) pg / 37.4 ± 5.3) pg / ml]. Eosinophil level in BALF was inhibited and the pulmonary inflammation was significantly relieved compared to asthma model group. Conclusion: Intratracheally administered BCG DNA can induce IL 12 and IFN γ secretion, inhibit Th2 response which can relieve allergic airway inflammation and provide a new way in the treatment and prevention of asthma.