In this research project, at first, two new thermally stable poly(benzimidazole-amide) derived from1,3-bis(5-amino-1H-benzimidazole-2-yl)benzene as diamine and (2s)-5-(4-methyl-2-phthalymidyl pentanoyl amino) Isophthalic acid containing amino acid fragment and 5-hydroxy Isophthalic acid via direct polycondensation reaction were prepared. Polymerization reactions were performed via classical heating method .Solvents commonly used in ?chemical reactions are highly toxic and have adverse effects on human health and the environment? pass. To prevent this, the polymerization reactions were carried out in tetrabutylammonium bromide as a molten ionic liquid salt and in the presence of triphenyl phosphite as the condensing agent. Optimized conditions based on time were investigated for polymerization. Structure of the obtained polymers was studied by Fourier transform infrared spectroscopy (FT-IR),1H nuclear magnetic resonance, and elemental analysis. Thermal stability of the polymers was studied using Thermogravimetric analysis (TGA) technique. The obtained results showed that the polymers have good thermal stability. The resulting PBIAs exhibited good yields and were soluble in polar aprotic organic solvents such as N,N-dimethyl acetamide (DMAc), N,N-dimethyl formamide (DMF) and dimethyl sulfoxide (DMSO). Crystallinity of the polymers was investigated by X-ray diffraction (XRD) technique. The diffraction patterns showed that the synthesized polymers had amorphous structures. This property is due to the polymer structure and also the presence of methyl and methylene flexible groups, which prevent the interaction between the polymer chains. The surface morphology of polymers was also studied by field emission scanning electron microscopy (FE-SEM) analysis. The resulting images showed that the polymer particles were almost spherical. In the next section, in order to better interaction and great dispersion of graphite layers in the polymer matrix, graphene oxide were prepared and study with different analytical techniques such as FT-IR, XRD, TGA, FE-SEM and Raman spectroscopy. Finally, polymer-based nanocomposites containing graphene oxide were prepared. By ultrasonic-assisted solution blending method, graphene oxide were dispersed in the polymer matrix with different weight percentages of 5,10 and 15% by weight relative to the weight of the polymer and the related nanocomposites were prepared. The fabricated composites were investigated and studied by different analytical methods like FT-IR, XRD, TGA, FE-SEM and transmission electron microscopy (TEM). The Obtained micrographs from FE-SEM and TEM indicate uniform dispersion of functionalized graphene oxide in the polymer matrix.