The structures and spectroscopic properties of a series of (C^N)₂Ir(idpt) [C^N= 2-phenylpyridine(1), 2-(5-fluorophenyl)pyridine(2), 2-(4,5,6-trifluorophenyl)pyridine(3), idpt= imidodiphosphinate] complexes were investigated by the density functional methods. We first optimized geometrical structure in ground state of complexes 1-3, at the B3LYP/LanL2DZ levels, and the excited state structures by selected UB3LYP/LanL2DZ functional. The calculated bond lengths of Ir-N(1), Ir-C(1), and Ir-O(1) in the ground state agree well with the corresponding experimental results. At the TD-DFT and CPCM levels, 1-3 give rise to lower energy absorptions at 447(1), 452(2), 424(3) nm and corresponding phosphorescent emissions at 541(1), 499(2), 466(3) nm, respectively. The HOMOs of 1-3 are mainly localized on the metal and bidentate ligands, while the LUMOs are the π* type orbital of bidentate ligands. Therefore, the transition of 1-3 were assigned to the metal-to-ligand and ligand-to-ligand charge transfer (MLCT/LLCT) transition. It is shown that the emitting color are significantly dominated by the phenylpyridine ligand itself and F-substituent group.