The poly(urethane-imide) (PUI) which uses isophorone diisocyanate, dispersed red 19 (DR-19), and pyromellitic dianhydride is synthesized. The PUI is characterized by Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The results of DSC and TGA indicate that the PUI exhibits high thermal stability up to its glass-transition temperature of 209 C and 5% heat weight loss temperature of 296 C. The fluorescence spectra of PUI and DR-19 are measured, showing that the fluorescence effect of PUI is very similar to that of DR-19 except for the light decrease of fluorescence intensity, which indicates that the fluorescence effect of PUI is generated by the azobenzene groups in its macromolecular chains. The maximum molar absorption coefficient, absorption wavelength, and chromophores density are measured and used to calculate the third-order nonlinear optical coefficient \chi^{(3)} to be 3.96times10^{-13} esu. The nonlinear refractive index coefficient and molecular hyperpolarizability of PUI are also obtained. PUI is proved to have an excellent optical performance.