Nano-SiO2 modified waterborne polyurea is prepared by sol-gel method，with isophorone diisocyanate (IPDI), polyether amine (D2000), dimethylolpropionic acid (DMPA), ethylenediamine (EDA), 3-aminopropyltriethoxysilane (KH550)and triethyl Amine (TEA) as the main raw material，nano-silica (SiO2) as modifier. The structure and properties of the polymer were characterized by FTIR, TEM, SEM and TGA, and the effects of nano-SiO2 content on the performance of waterborne polyurea emulsion and film were studied. The results show that the particle size of waterborne polyurea increased, the viscosity increased, the water absorption of the coating decreased, the tensile strength increased first and then de-creased, the contact angle increased and the elongation at break decreases, with the increase of nano-SiO2 content. When the mass fraction of nano-SiO2 was 2%, the comprehensive performance of the coating film was the best, the water absorption rate and the contact angle was respectively 11.12% and 75.24?; Compared with the unmodified coating film, thermal decomposition temperature of the modified coating film was increased by 10 ?C approximately.