Abstract: In this study,cytotoxic effect and antiproliferative activity was detected by LDH assay and MTT assay.The effect of curcumin on cell cycle,apoptosis,mitochondrial membrane potential(△ψm) was analysed by flow cytometry. The caspase-3 and caspase-9 activities were assessed by caspase assay kit according to the manufacturer's instruction. The expression patterns of pro-apoptotic and anti-apoptotic Bcl-2 family proteins,cytochrome c,and PARP in curcumin treated MCF-7 cells were investigated by western blot. The results showed that curcumin had a markedly antiproliferative and cytotoxic activity against the MCF-7 cells in a dose-dependent manner. It was indicated that curcumin could result in G0/G1 phase and apoptosis of MCF-7cells. Curcumin increased △ψm,caspase-3,caspase-9,Bax,PARP expression,decreased Bcl-2 expression,and cytochrome c was found to be released from mitochondria to the cytosol. These results showed that curcumin exhibit anti-proliferation of human breast cancer MCF-7 cells via cell cycle arrest at the G0/G1 phase and apoptosis induced by mitochondrial pathway.