In this paper, we synthesized a series of curcumin analogs and evaluated their cytotoxicity against HepG2 cells. The results exhibited that the hydroxyl group at 3,3'-position play an essential role in enhancing their anti-proliferation activity. More importantly, 3,3'-hydroxy curcumin (1b) caused apoptosis in HepG2 cells with the ROS generation, which may be mainly composed of hydroxyl radicals (HO) and H2O2. The more cytotoxic activity and ROS-generating ability of 1b may be due to the more stable in (RPMI)-1640 medium and more massive uptake than curcumin. Then the generation of ROS can disrupt the intracellular redox balance, induce lipid peroxidation, cause the collapse of the mitochondrial membrane potential and ultimately lead to apoptosis. The results not only suggest that 3,3'-hydroxy curcumin (1b) may cause HepG2 cells apoptosis through ROS-mediated pathway, but also offer an important information for design of curcumin analog.