Abstract: Objective To observe the effects of recombinant IL-35-BCG(rBCG) neonatal inoculation on Tregs/Th17 balance in experimental asthma model. Methods We divided Neonatal BALB/c mice into 3 groups: IL-35-BCG, OVA and control groups. Within 2-3 days after birth, mice in IL-35-BCG group were inoculated with IL-35-BCG subcutaneously. At 4-week and 6-week, using the intraperitoneal OVA with alum sensitization protocol as mice in OVA group. Mice were used to perform asthma model and were challenged by an aerosol of OVA at 7- week for one week. Within 24 hours after the last atomization, the proportion of Th17 cells and Tregs cells was detected by flow cytometry. Results After sensitization, the proportion of Th17 cells and Tregs cells were no significant difference between the neonatal IL-35-BCG group and OVA group. After stimulation, the percentage of Th17 cells in IL-35-BCG group was significantly lower than in OVA group, while the percentage of Tregs cells was significantly higher than that in OVA group. Conclusion Tregs in IL-35-BCG group is significantly higher than those in OVA group and control group after stimulation, while the proportion of TH17 cells is significantly lower in the IL-35-BCG group than those in the other two groups. This further indicates that the anti-asthmatic effect of neonatal IL-35-BCG vaccination is mainly through changing Tregs/Th17 balance.