In this paper, 2,5-dibromo-o-pheneylenedimanine was obtained by the reduction of 4,7-dibromo-5,6-dinitro-2,1,3-benzothiadiazole, and reacted with 5,6-dione-1,10-phenanthroline, phenanthrenequinone, ace- naphthenequinone and benzyl to give four thiadiazole quinoxaline type monomers. Four donor-acceptor-donor (D-A-D) type polymers were papered by Suzuki coupling, which is the palladium diacetate (Pd(CH3COO)2) and ligand tricyclohexylphosphine-catalysed alternative copolymerization of four thiadiazole quinoxaline type monomers and M5, respectively. All monomers and polymers were characterized by FT-TR and ¹H NMR spectra. The optical properties of polymers solution in CHCl3, at neutral state and adding with different concentration of TFA were investigated by UV-Vis-Nir and fluorescence spectrometer. The experimental results showed that four kind of D-A-D type polymers have good sensitivity to low concentration of TFA, wherein polymer P2- P4 was sensitive to 10-2 mol/L of TFA and the color of the CHCl3 solution of P2-P4 changed significantly. There appears new wide absorption bands on the spectra of P2-P4 solution in CHCL at 600-1 000 nm followed by color changes. P2-P4 solution in CHCl3 have certain fluorescence properties, and the fluorescence intensity decreased when certain concentration of TFA was added to the polymer solution, wherein polymers P2-P4 has sensitivity to 10-3 mol/L of TFA. [ABSTRACT FROM AUTHOR]