Objective: To analyze the difference in microRNA expression in breast cancer cell lines of anthracycline anticancer drug resistance and explore the association between microRNA and drug resistance of breast cancer. Methods：The differentially expressed miRNAs between anthracycline anticancer drug-resistant breast cancer cell line MCF-7/ADM and its parental cell line MCF-7 were identified by miRNA profiling of these two cell lines using miRNA microarray；the results obtained by microarray profiling were vali－dated using real-time RT-PCR analysis. Results：Microarray analysis of MCF-7 to MCF-7/ADM cells identified 14 differentially ex－pressed genes，including 6 up-regulated and 8 down-regulated genes in MCF-7/ADM cells；real-time RT-PCR identified 6 microR－NAs that were differentially expressed between MCF-7 and MCF-7/ADM cells，including 3 up-regulated microRNAs：has-miR-221，has-miR-222，has-miR-106a，and 3 down-regulated microRNAs：has-let- 7a，has-miR -421，has-miR-23b in MCF-7/ADM cells.Conclusion：microRNA are differentially expressed in anthracycline anticancer drug-resistant breast cancer cell lines and its parental cell line，which suggests that microRNA may play a role in the development of drug-resistance in breast cancer cells.