We aimed to screen possible biomarkers associated with the molecular mechanism of breast cancer using microRNA (miRNA) microarray. The miRNAs expression profile GSE45666 was downloaded from Gene Expression Omnibus database, which included 101 genechips from breast tumor samples and 15 from adjacent breast normal tissue samples. Limma package in R language was used to screen and identify differentially expressed miRNAs (DE-miRNAs) which were classified as up-regulated and down-regulated groups. Then, target genes regulated by the two groups of DE-miRNA were predicted, followed by the functional and pathway enrichment analysis using the DAVID system. Totally, 130 DE-miRNAs were screened out, including 59 up-regulated DE-miRNAs and 71 down-regulated DE-miRNAs. The functional enrichment indicated that target genes of up- and down-regulated DE-miRNA may be most highly associated with positive regulation of gene expression and regulation of cellular metabolic process, respectively. Target genes regulated by the up- and down-regulated DE-miRNAs were mainly enriched in 13 and 14 pathways, respectively, and both were most significant in subcategories in cancer. In addition, we identified three important miRNAs (miR-142-3p, miR-483-5p and miR-483-3p) pivotal for the initiation and progression of this malignant tumor. MiR-142-3p, miR-483-5p and miR-483-3p are potential key factors for further understanding the molecular mechanism of breast cancer by affecting the normal physiological function of cell.