Amorphous rice husk silica with purity of 99.3% and the specific surface area value of 212 mP2P/g was obtained by burning the dilute HCl treated rice husk at 600°C. After being modified with γ-glycidyloxipropyltrimethoxysilane (KH-550), silica particles with size ranging from 30 to 50 nm were obtained and subsequently used as filler to prepare epoxy-based nanocomposites with 0, 1, 3, 5 and 10 wt% silica content. The mechanical properties of the nanocomposites were characterized in terms of tensile and flexural test. The morphologies of fracture surfaces of nanocomposites were investigated by scanning electron microscopy (SEM). Depending on the silica content, the stiffness, strength and toughness of the nanocomposites can be increased more or less compared with neat resin.