A novel Y-type polyester (7) containing 1-(2,4-dioxyethoxy)phenyl-2-{5-(1,2,2-tricyanovinyl)-2-thiophenyl)}ethenyl groups as NLO-chromophores was synthesized and characterized. Polymer 7 was soluble in common organic solvents such as DMF and DMSO. It showed thermal stability up to 300 degrees C in TGA with T(g) value obtained from DSC near 134 degrees C. The second harmonic generation (SHG) coefficient (d(33)) of poled polymer film at the 1,560 nm fundamental wavelength was around 6.74 x 10(-9) esu. The dipole alignment exhibited high thermal stability and there was no SHG decay below T(g) due to the partial main-chain character of polymer structure, which was acceptable for NLOdevice applications.