In our study, we conducted bioinformatics analysis based on AD RNA expression profile data in GEO, through differential expression analysis, WGCNA, miRNA–mRNA regulatory Network, PPI Network, ROC and LASSO Regression, Correlation analysis, qPCR and dual luciferase analysis methods, we screened the key miRNA-mRNA in the progress of AD: miR-26a-5p/PTGS2. This evidence concerns the gene PTGS2 and Alzheimer disease.