In this paper, composites with different contents of epoxy resin/nano-SiO2 were fabricated, the influence of compounding process on nano-SiO2 dispersion was studied, the microstructure and the relationship between impact strength and nano-SiO2 content were investigated. The results showed that the distribution of nano-SiO2 particles in the composites could be improved efficiently using high-speed shearing dispersion method. To composites with or without the coupling agent treatment, the impact strength grew with increasing nano-SiO2 content, and increase to a maximum value when nano-SiO2 content was 3wt.%. The maximum value was 75.4%, and 45.5% higher than that of monolithic epoxy resin respectively. With the nano-SiO2 content increased continually, the impact strength of composite materials decreased. The coupling agent treatment of nano-SiO2 administered to improve the impact strength of the composites.