Generally, PVAc (polyvinyl acetate) adhesive has weak strength properties with capability of using in wooden products such as wood adhesive. The carbon nanomaterial (CNF) is one of the most influential substances on the strength properties of polymer materials. Thus, the mechanical and thermal properties of polyvinyl acetate glue reinforced with carbon nanofibers were investigated in both modified and unmodified cases and in three levels of zero, 0.4 and 1.5% by weight of glue. Modified carbon nanofibres were used to improve the dispersion of (CNF) into polymeric matrix by surface chemical modification method. The results of the FTIR spectroscopy analysiswere confirmed an oxidation and presence of new functional groups on the surface of modified carbon nanofibers. Mentioned nanocomposites made by solvent molding method and the tensile properties, thermal behavior (TGA) and microstructure were evaluated. Transmission electron microscope (TEM) images indicated better dispersion of modified nanoparticles in 0.4 wt% than higher values in the polymer matrix. In addition, the tensile esults showed an improvement of mechanical behavior of nanocomposites (elasticity modulus, tensile strength, and fracture energy) due to the presence of modified nanoparticles. Improvement of these properties with modified carbon nanofibers was 2.4, 1.6 and 1.8 times respectively, compared to pure polyvinyl acetate. In addition, two stages of reduction mass relative observed than the pure adhesive in thermal stability of both nanocomposite series. Generally, the best tensile strength observed in nanocomposite specimens containing 0.4% w/w with modified carbon nanofibers.