To explore the mechanism of Bupleuri Radix in the treatment of four molecular types of breast cancer based on network pharmacology.Methods:The active components and targets of Bupleuri Radix were obtained from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform(TCMSP) and the Traditional Chinese Medicine Integrated Database(TCMID).The targets of four molecular types of breast cancer were retrieved from Genecards and OMIM.The common targets shared by the active components and breast cancer were identified and imported into STRING for the establishment of the protein-protein interaction(PPI) network.The frequency of association of the targets was counted in Cytoscape.The gene ontology(GO) annotation of the common targets was conducted in R studio.The Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway enrichment of the target genes was carried out with DAVID.The results were expressed as network diagram by Cytoscape.Results:The active components of Bupleuri Radix and breast cancer shared 101 common targets,which were mainly involved in RNA polymerase Ⅱ transcription factor binding,ubiquitin-like protein ligase binding,kinase regulatory activity,etc.The enriched pathways include MAPK,P53,and VEGF signaling pathways.Conclusion:Bupleuri Radix treats four molecular types of breast cancer through multiple targets and multiple signaling pathways,which may be related to the regulation of the proliferation,apoptosis,and metastasis of tumor cells.