The object of this paper is to study the effect of silica nanoparticles (SiO2 NPs) on waterborne polyurethane films (5×10-3 to 5wt % SiO2 NPs). The Nanocompounds’ properties were analyzed by thermogravimetric analyzer (TGA), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR) and dynamic mechanical analyzer (DMA). From the results, the nanocomposites degraded at a higher temperature than pure PU matrix. Moreover, the temperature where the weight loss reached 50% was shifted by 57oC towards higher temperature when the silica nanoparticle content was 5 wt%. The crystallinity, mechanical strength as well as thermostability the PU were influenced by the concentration of silica nanoparticles.