A Ru(II) polypyridyl complex [Ru(bpy)2(HMSPIP)](ClO4)2 (1) (bpy=2,2'-bipyridine, HMSPIP=2-(4-methylsulfonyl)phenyl-1H-imidazo[4,5-f][1,10] phenanthroline) was synthesized. The IC50 value of the complex against human hepatocellular cell BEL-7402 is 21.6±2.7 μM. The complex shows no cytotoxic activity toward human lung adenocarcinoma cell A549, human osteosarcoma cell MG-63 and human breast cancer cell SK-BR-3 cells. It is easily for complex 1 to be taken up by BEL-7402 cells. The complex can enhance the reactive oxygen species (ROS) levels and induce the decrease in the mitochondrial membrane potential. The complex inhibits the cell growth in BEL-7402 cells at G2/M phase. Complex 1 can regulate the expression of Bcl-2 family proteins. The results show that the complex induces apoptosis of BEL-7402 cells through a ROS-mediated mitochondrial dysfunction pathway.