Abstract: Objective To investigate the expression pattern of hsa-miR-145-5p in the plasma of patients in pancreatic cancer and normal person,and explore the feasibility of hsa-miR-145-5p as a diagnostic marker for pancreatic cancer,and further clarify its possible regulatory mechanism in the development and progression of pancreatic cancer. Methods Target genes prediction and functional analysis of hsa-miR-145-5p by bioinformatics method.MiRanda,TargetScan and RNAhybrid software were used to predict the target genes of hsa-miR-145-5p and the target genes supported by experimental data,and GO enrichment,KEGG Pathway enrichment analysis and protein interaction analysis were performed to study the function of target genes.RT-qPCR was used to detect the expression of hsa-miR-145-5p in pancreatic cancer and normal control group. Results hsa-miR-145-5p mature sequences were high conserved in several species.The number of target genes were predicted to be 8 679,and the number of target genes that the experimental data supported was 1 408.The GO enrichment analysis of the target genes,which was supported by the experimental data,was mainly concentrated in the biological processes and functions such as intracellular transport,gene expression regulation,intracellular signal transduction,cell growth regulation,energy metabolism,and so on (FDR<0.01).KEGG pathway enrichment analysis was significantly enriched in p53 signaling pathway,ErbB signaling pathway,MAPK signaling pathway,chronic myeloid leukemia,bladder cancer,glioma,prostate cancer,pancreatic cancer,and so on (P<0.01).Compared with the normal group,the expression of hsa-miR-145-5p was down regulated. Conclusion hsa-miR-145-5p regulates multiple tumor related genes,plays an important regulatory role in the biological process of pancreatic cancer and provides clues for the study of a miRNA diagnostic marker in pancreatic cancer.