The geometrical and spectral characteristics of [(tpy)Ru(tHI-X)]2+[(tpy=2,2′:6′,2′′- terpyridine, tHI =2-(4-[2,2′:6′,2′′] terpyridine-4-ylphenyl)-1H phenanthrene [9,10-d]-imidazole, X=none(1), F(2)] complexes were studied by the density functional theory (DFT) method. The geometric configuration of the ground and excited state of the complexes 1 and 2 was optimized by using the B3LYP and UB3LYP functional in the density functional method of Gaussian 09 program, respectively. The absorption and emission spectra of the two molecules in DMSO solution were obtained by combining the polarization continuum model. The calculated results show that the ground state bond lengths and absorption spectrum of complex 1 are in good agreement with the corresponding experimental values, when F-groups are introduced, the H atoms on the F-and N7-H have strong interaction, to generate a new F-H bond. At the TD-DFT and PCM levels, 1-2 give rise to absorptions at 505 and 628 nm and phosphorescent emissions at 713 and 744 nm, respectively. The HOMOs of 1-2 are mainly localized on the tHI ligand, while the LUMOs are the π*(tpy) type orbital. Therefore, the transitions of 1-2 are all attributed to [π(tHI)]→[π*(tpy)] charge transfer. The 3LLCT transition property of the lowest excited state is the main factor leading to the radiation transition.