The interaction of Ru(phen)2(dppx)2+(phen=1.10-phenanthroline, dppx=7,8-dimethyl dipyrido[3,2-a:2′,3′-c]phenazine) and the calf thymus DNA were studied with fluorescence and ultraviolet visible absorption spectroscopy. Fe(CN)64and NaCl can not quench the fluorescence of Ru(phen)2(dppx)2+-DNA. which indicate that Ru(phen)2(dppx)2+intercalate into the double helix of DNA. The ultraviolet visible absorption spectrum of Ru(phen)2(dppx)2+calf thymus DNA, and the results of their interaction reveal that Ru(phen)2(dppx)2+intercalate into the double helix of DNA via the ligand dppx.