The effects of the cyclin E expression levels on chemotherapeutic sensitivity of breast cancer cell line were explored. After the cyclin E expression was knockdown in MDA-MB-435 by RNA interference, FACS analysis and SA-beta-gal staining were used to evaluate the response sensitivity of breast cancer cells to DNA damage drugs (adriamycin, etc.). Adriamycin could induce G1 arrest in cyclin E knockdown MDA-MB-435 breast cell line and increase the percentage of cell senescence in cyclin E knockdown MDA-MB-435 cells. It was suggested that cyclin E knockdown could increase the chemotherapeutic sensitivity of breast cancer cells to DNA damage drugs.