Nano-sized SiO2 particles were prepared via the sol-gel process, and evenly dispersed in the polyurethane resin. The tensile strength and 100% modulus of the polyurethane doped with SiO2 were increased and the content of SiO2 has an optimum value. Elongation at break had a downtrend at first and an ascending trend afterward with the increase of SiO2. The addition of nano-sized SiO2 not only increased the storage modulus but also improved the peak of tan delta of the polymer. Nano-sized SiO2 hardly affected the low temperature-resistant properties, but improved the heat-resistant properties of the resin.