Objective To elucidate the airway inflammation status in mice infected with respiratory syncytial virus (RSV), and whether the inflammation could be alleviated by small interference RNA (siRNA) targeting specific RSV gene. Methods BALB/c mice were infected with RSV via intranasal instillation of RSV suspension, and were then treated with specific siRNA targeting RSV-M2 gene. ELISA assay was used to detect the levels of IFN-γ, IL-12 and IL-10 and Microscope was used to count white blood cells in bronchoalveolar lavage fluid(BALF). Results After RSV infection, a significant increase in leukocytes count was observed in BALF. Differential count showed a rise in the percentage of neutrophils, eosinophil, especially lymphocytes and a reduction of the percentage of monocytes and macrophages( P＜0.05 ).The levels of IFN-γ, IL-12 and IL-10 were also increased(P＜0.05). Furthermore, the leukocytes count,the percentage of lymphocytes, neutrophils and eosinophil, and the levels of IFN-γ, IL-12 and IL-10in BALF were decreased accordingly while the mice were given higher concentrations of siRNA ( P＜0.05 ).Conclusion RSV caused airway inflammation in BALB/c mice, which may be alleviated by RNAi technology.