In this paper, nano-silica particles were incorporated to a fused silica-boron nitride dual phase ceramics originally using micrometer sized particles as starting powders. Effects of nano-silica content on density, sintering behavior, mechanical properties and microstructure of the dual phase ceramics were investigated. It was found that with the addition of nano-silica particles, the density and mechanical properties of the dual phase ceramics increased. Flexural strength and fracture toughness of them attained to 51.4MPa and 0.8MPa·m1/2, respectively. The increased density and spatial network structure of fused silica attribute to the improvement of the mechanical properties of the dual phase ceramics.