Theoretical study on diphenyl terephthalate molecules has been carried out at B3LYP/6-31＋G* level to obtain optimized equilibrium structures, vibrational spectra, electronic spectra and nonlinear optical proper-ties. The effects of 4-substituting terminal groups on the spectra and nonlinear optical properties have been discussed. The results show that the introduction of 4-substituting terminal groups has little effect on the structure. The length of alkyl chains has little effect on the vibrational spectra. The introduction of CN makes C＝O stretching vibration frequencies blue-shifted 9 cm^－1. The first excited state electronic transition energy has been calculated using time-dependent density functional theory. The results show that the largest absorption spectra of the title compounds were obtained from the p→p* electron transition from the highest occupied molecular orbital to the lowest unoccupied molecular orbital, and λ_max was obtained in 313～375 nm, belonging to the UV absorption area. The introduction of a strong electron-donor group results in enlarging the second-order nonlinear optical proper-ties.