Objective:To investigate the mechanism of Yunshi Ganmao Heji against respiratory syncytial virus (RSV) infection based on network pharmacology and in vivo experiments. Methods:Network pharmacological prediction: Several databases including TCMSP and GeneCards were used to predict the active ingredients and targets of Yunshi Ganmao Heji in the intervention of RSV infection. Cytoscape 3.2.1 software was used to construct the traditional Chinese medicine component-disease target network diagram. The interactions between proteins were analyzed by STRING database. GO functional enrichment analysis and KEGG pathway enrichment analysis were performed using Metascape database. Molecular docking technology was used to verify the results of network pharmacology. Experimental verification of Yunshi Ganmao Heji for the intervention of RSV infection: A mouse model of RSV infection was established through intranasal infection. After the administration of Yunshi Ganmao Heji, blood routine test results, lung indexes and pathological changes in lung tissue were analyzed. Peripheral blood T cell subsets were detected by flow cytometry. The levels of TNF-α, IL-6 and IL-1β in serum were detected by ELISA. RT-PCR was used to detect the relative expression of TLR4, NF-κB and RSV-N gene at mRNA level in lung tissues.Results:A total of 41 active ingredients of Yunshi Ganmao Heji and 111 drug targets for RSV infection were obtained. Besides, 167 signaling pathways mainly including PI3K/AKT, MAPK and Toll-like receptor signaling pathways were obtained. Molecular docking results showed that the binding energies of luteotin, kaempferol and quercetin, three active ingredients of Yunshi Ganmao Heji, with RSV-G, RSV-F, PI3K, AKT1 and Bcl-2 were less than 0 kcal/mol. In vivo experiment results showed that compared with RSV group, the counts of white blood cells and lymphocytes increased and the lung index decreased in high-dose Yunshi Ganmao Heji group, with statistically significant difference ( P<0.05). HE staining showed pulmonary hyperplasia, thickened alveolar wall and inflammatory cell infiltration in interstitium in RSV group. Alveoli in ribavirin group as well as low-dose, medium-dose and high-dose Yunshi Ganmao Heji groups tended to be of uniform size, and the alveolar walls was roughly uniform in thickness. Compared with RSV group, the low-dose, medium-dose and high-dose Yunshi Ganmao Heji groups showed significantly increased numbers of CD3 +, CD4 + and CD8 + T lymphocytes, decreased CD4 + /CD8 + T cell ratio, lower levels of TNF-α, IL-6, IL-1β in serum, and reduced viral load and inhibited expression of TLR4 and NF-κB at mRNA level in lung tissues ( P<0.05). Conclusions:Yunshi Ganmao Heji can regulate RSV infection by targeting multiple targets and pathways with several active ingredients. Its main functions are to alleviate pathological injury in lung tissues and reduce inflammatory response, and the possible mechanism underlying the antiviral functions may be related to its inhibitory effect on the activation of TLR4/NF-κB pathway.