In this study, the surface of Zinc oxide nanoparticles (ZnO NPs) was modified with optically active and bioactive dicarboxylic acids (DA)s containing different natural amino acids such as L-leucine, L-alanine, L-phenylalanine, L-methionine and L-valine. The surface modification was essential for decreasing of the agglomeration of and improving of their compatibility with organic and biological environments such as polymer matrix. The process was accomplished under ultrasonic method as a fast, low cost and green way. The prepared DAs-modified ZnO NPs were studied with FT-IR, XRD, TEM, FE-SEM and TGA techniques. Thermal analysis confirmed grafting of DAs on the surface ofNPs. From comparing of TGA curve of modified ZnO NPs with its pure can be concluded that the presence of DA on the surface of NPs is about 11 wt%. According to the normal distribution curve, modified ZnO NPs with DAs based on different amino acids have good dispersion. In the other investigation, poly(amide-imide)/ZnO nanocomposites (PAI/ZnO NCs) were successfully fabricated through ultrasonic technique. The most important aims of this project were the effect of surface modification on the dispersion of ZnO NPs, also the influence of ZnO on the thermal stability and UV absorption of the polymer matrix. For this purpose at the first the optically active PAI was produced by the polycondensation reaction of N-trimellitylimido-L-alanine DA with 4,4'-diaminodiphenylmethane in the presence of triphenyl phosphite and the molten tetra-n-butylammonium bromide. Then, NCs containing 4, 8 and 12 wt% of DA-modified ZnO NPs were prepared via ultrasonic method through blending of DA-modified ZnONPswith the PAI. The properties of the synthesized NCs were studied by FT-IR, XRD, UV–vis, FE-SEM, TEM and TGA techniques. Comparing of the normal distribution curve of NCs (4, 8 and 12%) showed the better dispersion of the ZnO NPs in to the polymer matrix for NC of 12 wt% due to its narrower curve. The UV absorption was improved by employing of ZnO NPs as efficient filler in NCs. T5 and T10 of the composites dramatically increased about 10-20 °C and 5 °C respectively, when compared with neat PAI..