The geometries and spectroscopic properties of [Ir(ppy)₂(ppz)]⁺(1), [Ir(ppy)₂(ppz)]⁺(2), [Ir(ppy)₂(ppz)]⁺ (3) (3 and 2 are different in the connection position of benzene ring) [ppy=phenylpyridine, ppz=(2-pyridyl)pyrazole, ph=phenyl] complexes were studied theoretically. B3LYP functional and single excited configuration interaction (CIS) methods were used to optimize the S₀ and T₁ structures. The absorption and emission spectra of the complexes in CH2Cl2 solution were calculated by time dependent density functional theory (TD-DFT) and polarized continuum model (PCM). The results show that Ir-N3 and Ir-N4 obtained by the ground state optimization are in good agreement with the corresponding experimental values. The lowest energy absorption of complexes 1-3 is 447.91 nm, 456.52 nm and 516.90 nm, and the phosphorescence emission is 512.02 nm, 501.14 nm and 562.29 nm, respectively. The highest occupied molecule orbit (HOMO) of complexes 1-3 is mainly occupied by Ir and ppy, and the lowest unoccupied orbit (LUMO) is occupied by ppz ligands π* orbit. Therefore, this transition is referred to as the metal to ppz ligand and ppy ligand to ppz ligand charge transfer (MLCT/LLCT) transition. Moreover, the absorption and emission of these complexes are greatly influenced by ppy and ppz ligands.