2,3- Di-( 2'- hydroxyethoxy)- 4'- nitrostilbene ( 3) was prepared and condensed with terephthaloyl chloride and adipoyl chloride to yield novel Y- type polyesters ( 4 - 5) containing the NLO- chromophores dioxynitrostilbenyl groups, which constituted parts of the polymer backbones. Polymers 4 - 5 were soluble in common organic solvents such as acetone and dimethylsulfoxide. They showed thermal stability up to 300 degrees C in thermogravimetric analysis with glass- transition temperatures obtained from differential scanning calorimetry in the range of 83 - 95 degrees C. The second harmonic generation ( SHG) coefficients ( d(33)) of poled polymer films at the 1064cm(-1) fundamental wavelength were around 3.68 x10(-9) esu. The dipole alignment exhibited high thermal stability up to the glass- transition temperature due to the partial main- chain character of polymer structure, which was acceptable for NLO device applications.