Polyvinylalcohol/Silica (PVA/SiO2) nanocomposites with different SiO2 contents are synthesized by employing a novel self-assembly monolayer (SAM) technique. The influence of the silica on dynamic mechanical properties of the nanocomposites is investigated by conducting dynamic mechanical analysis (DMA) and quasi-thermal mechanical analysis (Q-TMA). It is found that the storage modulus (E′), loss factor (tga), glass transition temperature (Tg), and activation energy (Ea) of prepared nanocomposites all show a strong dependence on the SiO2 content. The Q-TMA results indicate that under a constant force, the elasticity of nanocomposites decreases with SiO2 content, and the softening temperature moves to a higher temperature when more SiO2 is added.