A novel T-type polyurethane 7 containing 1-(2,5-dioxyphenyl)-2-{5-(1,2,2-tricyanovinyl)-2-thienyl}ethene groups as nonlinear optical (NLO) chromophores was prepared and characterized. Polyurethane 7 is soluble in common organic solvents such as DMF and DMSO. Polymer 7 shows a thermal stability up to 270 degrees C from TGA thermogram and the Tg value obtained from DSC thermogram is around 155 degrees C. The second harmonic generation (SHG) coefficient (d33) of poled polymer film at 1560nm fundamental wavelength is 3.56x10-9esu. The dipole alignment exhibits a thermal stability even at 5 degrees C higher than Tg, and there is no SHG decay below 160 degrees C due to the partial main-chain character of the polymer structure, which is acceptable for nonlinear optical device applications.