A new diimide-dicarboxylic acid, 1,2-bis(4-trimellitimidophenoxy)benzene[1,2-BTPB], having flexible 1,2-bis(4-phenoxy)benzene unit was synthesized by the condensation reaction of 1,2-bis(4-aminophenoxy)benzene with trimellitic anhydride in N,N-dimethylformamide (DMF). A series of new poly(amide-imide)s were prepared by direct polycondensation of 1,2-BTPB and aromatic didmines containing multiaromatic rings linked with various flexible or bulky linkages in N-methyl-2-pyrroli-done(NMP), using triphenyl phosphite and pyridine as condensing agents. The resultant polymers had moderate inherent viscosities of 0.31～O.78 dL/g and wide-angle X-ray diffractograms revealed that the polymers were amorphous. Most of polymers exhibited good solubility and could be readily dissolved in various solvents such as DMF, NMP, N,N-dimethylacetamide, N,N-dimethylsulfoxide, m-cresol, and pyridine. The glass transition temperatures of the polymers occurred over the temperature range of 213~302$^{circ}C$ in their differential scanning calorimetry(DSC) curves and their 10% weight loss temperature in air and nitrogen were in the range of 485～53$0^{circ}C$ and 480～55$0^{circ}C$, respectively, by thermo-gravimetric analysis(TGA). All the polymers did not lose weight below 40$0^{circ}C$ in air and nitrogen, and their DSC curves also revealed similar decomposition behavior to that of TGA with no transition below the decompo,iition temperatures.