The incidence of mild cognitive impairment (MCI) and diabetes mellitus (DM) is increasing year by year. Clinical findings show that Banxia Xiexin Decoction (BXD) can be combined to treat MCI and DM. However, the principle and mechanism of BXD in treating MCI and DM remain unclear. In this study, to explore the common mechanism of BXD in treating MCI and DM by using the method of network pharmacology. Traditional Chinese Medicine Systems Pharmacology Database (TCMSP) was used to screen the main active components of BXD, as well as to predict and screen its potential targets. Using Online Mendelian Inheritance in Man (OMIM), Therapeutic Target Database (TTD), DisGeNET, GeneCards to select the target proteins of two diseases, and intersecting the drug target and the disease target to obtain the common target of drug diseases, which is imported into cytoscape software to draw the network diagram of "drug components-target diseases" and the interaction network diagram between the common target proteins. According to the Database for Annotation, Visualization and Integrated Discovery (DAVID) database, we analyzed the common targets using two methods, gene ontology Kyoto Encyclopedia of Genes and Genomes (KEGG) biological pathway enrichment analysis and Gene Ontology (GO) function enrichment analysis, as well as studied the interaction mechanism of the two diseases, with the results validated using molecular docking. A total of 267 main active components of BXD were screened, together with the two diseases shared 233 common targets. The top five key targets identified by the topological analysis were TP53, AKT1, STAT3, TNF, and MAPK3. Go enrichment results indicated that it was primarily related to response to drug, extracellular space, enzyme binding, RNA polymerase II transcription factor activity, ligand-activated sequence-specific DNA binding. t KEGG enrichment pathway analysis identified 20 significant pathways, the majority of which are AGE-RAGE signaling pathways in diabetic complications, lipid and atherosclerosis, fluid shear stress and atherosclerosis, IL-17 signaling pathway, TNF signaling pathway, and so on. The results of molecular docking revealed that the key components of BXD, baicalein, licochalcone a, quercetin, and naringenin, had strong binding ability with core targets TP53, AKT1, STAT3, TNF, MAPK3. BXD can treat MCI and DM by multi-targets and multi-channels,and plays a role of "homotherapy for heteropathy" mainly through response to drug, positive regulation of gene expression, extracellular space and enzyme binding and other ways.