Objective：To discuss the clinical effect of Yinqiao powder on respiratory system of mice model infected with respiratory syncytial virus and its mechanism.Methods： Mice were divided into 6 groups randomly，namely the normal group，the model group，the group of low-dose Yinqiao powder，the group of medium-dose Yinqiao powder，the group of high-dose Yinqiao powder and the ribavirin group，9 mice in each group.Except the normal group，mice in other groups were infected with 50μL nasal drops of TCID50 respiratory syncytial virus(RSV)fluid after received light anesthesia with ether.The group of low-dose Yinqiao powder，the group of medium-dose Yinqiao powder and the group of high-dose Yinqiao powder were respectively given 600 mg/(kg·d)，300 mg/(kg·d)and 150 mg/(kg·d)of Yinqiao powder by gavage，while the ribavirin group was given 150 mg/(kg·d)of ribavirin by gavage.The group of low-dose Yinqiao powder， the group of medium-dose Yinqiao powder，the group of high-dose Yinqiao powder and the ribavirin group began to receive medication by gavage one day before infection，continuously lasting for 5 days，while the normal group and the model group were given equal volume of distilled water by gavage.Lung indexes were calculated by weighing body mass and lung weight of mice.HE staining was used to detect the pathological changes in the nasal mucosa and inflammatory cells infiltration in the lung tissueof mice.The levels of interleukin-1β(IL-1β)，tumor necrosis factor-α(TNF-α)and interleukin-6(IL-6)in alveolar lavage fluid were detected by enzyme-linked immunosorbent assay.The expressions of NALP3 inflammasome，apoptosis-associated microparticles(ASC)and caspase-1 in lung tissue were detected by real-time quantitative PCR and Western blot.Results：Compared with those in the normal group，the lung indexes of the model group were increased significantly，the expression of TNF-α，IL-1β，and IL-6 in alveolar lavage fluid was increased evidently，and the expression of NALP3，ASC，caspase-1 mRNA and protein in lung tissue were obviously increased，differences being significant(P＜0.05).Compared with those in the model group，the lung indexes of mice in the groups of Yinqiao powder and the ribavirin group were evidently decreased， the expression of TNF-α， IL-1β， and IL-6 in alveolar lavage fluid was significantly decreased， and the expression of NALP3，ASC， caspase-1 mRNA and protein in lung tissue was obviously decreased， differences being significant(P＜0.05).Compared with those in the ribavirin group，the expression of TNF-α and IL-1β in the alveolar lavage fluid of mice in the group of medium-dose Yinqiao powder was higher，and the expression of NALP3 and caspase-1 mRNA in lung tissue were higher， while the lung indexes of mice in the group of low-dose Yinqiao powder were higher， the expression of TNF-α，IL-1β and IL-6 in the alveolar lavage fluid was higher，and the expression of NALP3，ASC，caspase-1 mRNA and protein in lung tissue were higher，differences being significant(P＜0.05).Conclusion：Yinqiao powder can improve respiratory system inflammation resulting from infection of respiratory syncytial virus，and its mechanism is related to the inhibition of the activation of NALP3 inflammasome and the secretion of inflammatory cytokines.