To investigate the difference of miRNA expression between lung cancer cell A549 and its DDP-resistant cell strain A549/DDP, we have employed miRNA microarray expression to discover the difference expression of miRNAs of A549 cells and A549/DDP. We conducted RT-qPCR to examine the expression levels of top differential expressed miRNAs, namely, miR-197-5p, miR-4443, miR-642a-3p, miR-27b-3p and miR-100-5p, confirming low variability between two methods. Overall design: The A549/DDP was established from A549 in our laboratory, by exposing A549 to gradually increasing DDP concentrations, until the final concentration at 1μg/ml. To avoid the influence of drug to the A549/DDP cells, they were cultured in a drug-free medium for at least two weeks before gene expression analysis. miRNA expression of A549 and A549/DDP was then analzyed.