The present work aims to evaluate the influence of surface functionalizated nano-silicon dioxide (SiO2) on mechanical properties of polyamide-6 (PA 6) matrix. Since the silica is a hydrophilic mineral filler and the PA 6 is an organophilic polymer matrix there is poor interaction between them. To overcome this problem, the nanofiller surface was chemically modified with 3-aminopropyltrimethoxysilane (APTMS) silane agent by the incorporation of a reactive chemical group to interact with the polymer. This agent was chosen by the presence of the NH2 group at the end of its chain, which is expected to interact by hydrogen bonds with the amide group of the polymer, thus ensuring good interaction filler-polymer contributing to improve the mechanical properties of the nanocomposite. The unmodified and modified SiO2/APTMS were evaluated by Nuclear Magnetic Resonance spectroscopy (NMR) to support that the silane agent was grafted in the filler surface. After the surface modification, the fillers (both modified and unmodified) were mixed with the polymer on HAAKE mixer in variable contents: 1%, 2% and 4 wt%. Besides the amount of nanoparticles added to the polymer, other three process parameters were analyzed in the HAAKE processing step, in order to verify their influence on mixture efficiency (nanoparticles dispersion and distribution) and degradation, which are: residence time for degradation estimation, shear rate and mixture efficiency through chamber filling and rotational speed. Then, the PA6/SiO2 nanocomposites were compression molded to obtain plates and after that the specimen’s crystallinity was measured by differential scanning calorimetry (DSC) and correlated with mechanical properties obtained by tensile tests; degradation was evaluated by intrinsic viscosity analysis.