The spectral characteristics of [Ir(ppy)2(py-H)]+(1), [Ir(ppy)2(py-pr)]+(2), [Ir(ppy)2 (py-pz)]+(3) [ppy = phenylpyridine, py = bis(pyrazol-1-yl)methane, pr = pyrrole, pz = pyrazole] complexes were studied theoretically. The density functional and the single excitation configuration interaction method are used to optimize the ground state and excited state structure, and the time-dependent density functional theory combined with the polarized continuum model is used to calculate the absorption and emission spectra of complexes 1-3 in the CH2Cl2 solution. The bond lengths of Ir-N1, Ir-N4 and Ir-N6 in the ground state are in good agreement with the corresponding experimental values, and the geometric configuration of the excited state changes little relative to the ground state, which is consistent with the stokes frequency shift phenomenon. The lowest energy absorption of complexes 1-3 at 399.07 nm, 401.68 nm and 396.15 nm, and the phosphorescence emission at 513.00 nm, 513.78 nm and 510.38 nm, respectively. The highest occupied molecular orbital (HOMO) of these complexes is mainly occupied by Ir and ppy ligand, while the lowest unoccupied molecular orbital (LUMO) of 1 and 2 is occupied by the π*-type orbital of the ppy ligand, this transition is referred to as the metal to ligand and intraligand charge transfer transition(MLCT/ILCT). However, the LUMO of molecule 3 is occupied by the π* orbitals of the ppy and py ligands, its transition property is only the transition from metal to py-pz ligand (MLCT). The research results show that the introduction of substituent groups on the non-conjugated ligand py will not have an important effect on the color of these complexes.