The polyamideimides having NLO-active chromophores were synthesized by direct polycondensation of 4-[N,N''-bis(2-aminoethyl)amino]-4''-nitrostilbene (DANS-diamine) with oxy-bis[N-(4-phenylene)-trimellitic imide] (BCI) and N-(3-carboxyphenyl)-trimellitimide (BTI) without an imidization process. The direct polycondensation of NLO polyamideimides without a curing step may ameliorate the optical property of NLO polymers by reducing the optical propagation loss. The resulting polymers were highly soluble in aprotic polar solvents such as DMF, DMAc, NMP, etc.. The NLO polyamideimides had the inherent viscosity range of 0.19∼0.33 dL/g. Molecular structural characterization for the resulting polymers was achieved by ¹H-NMR, FT-IR, and UV-visible spectroscopies. Their glass transition temperature was in the range of 178∼224℃ and they showed thermal stability up to 220℃. The polymer solutions could be spin coated on the indium-tinoxide (ITO) glass or quartz disc substrates to form the optical quality thin films. The electro-optic coefficients (r₃₃) at the wavelength of 1.3㎛, measured by simple reflection method, for polymer thin films poled around the glass transition temperature were 1.9 and 6.8 pm/V.