Objective To explore the molecular mechanism of Xiaojin Pills in the treatment of breast cancer using an integrated network pharmacology and experimental verification.Methods The chemical components and potential targets of Xiaojin Pills were obtained from TCMSP,TCM-ID,ETCM and SwissTargetPrediction databases.Breast cancer related targets were collected from GeneCards,OMIM and KEGG databases.The overlapped targets were imported into STRING database to analysis a protein-protein interaction(PPI).The key targets of PPI networks were screened based on node topology parameter values through Cytoscape 3.8.0.DAVID database was used to analyze the GO and KEGG pathway enrichment to build drug-chemical components-key targets-signaling pathway network.The breast cancer cell lines MDA-MB-231 and SK-BR-3 were used to study the effects of Xiaojin Pills extract on cell apoptosis,migration and invasion,and to verify the key pathway obtained by enrichment analysis.Results Totally 181 chemical components in Xiaojin Pills were obtained,including quercetin,myricetin,pinocembrin and β-sitosterol.615 potential targets were identified for the anti-breast cancer effects of Xiaojin Pills.After overlapping,170 key targets against breast cancer were identified based on the topological analysis,which included SRC,ERK1/2,AKT1,EGFR,etc.KEGG analysis enriched pathways including pathways in cancer,MAPK signaling pathway,endocrine resistance,PI3K-AKT signaling pathway,EGFR tyrosine kinase inhibitor resistance,apoptosis,and HIF-1 signaling pathway,which may play important roles in the therapeutic effects of Xiaojin Pills against breast cancer.GO enrichment was involved in protein phosphorylation,inflammatory response,negative regulation of apoptosis,and positive regulation of ERK1 and ERK2 cascades.Cell experiments showed that Xiaojin Pills further induced mitochondria-dependent apoptosis by inhibiting the activation of MAPK and PI3K-AKT pathways.At the same time,the expressions of ZO-1 and β-catenin increased,and the epithelial-mesenchymal transformation process was reversed to inhibit the metastasis of breast cancer cells.Conclusion The key targets and signaling pathways of Xiaojin Pills in the treatment of breast cancer are studied through network pharmacology combined with in vitro experiments,which provided a basis for further study of its pharmacodynamic material basis,mechanism of action and clinical application.