This experimental study reported electrical properties of linear low density polyethylene (LLDPE)/SiO ₂ nanocomposites prepared by melt blending methods. The effects of surface modified SiO ₂ nanoparticles on the microstructure, space charge distribution and thermally stimulated current were investigated. The addition of surface modified nanoparticles increases the amount of spherulites and decreases their sizes. It is found that the LDPE/SiO ₂ interface shows significant influence on electrical properties of nanocomposites. The addition of SiO ₂ nanoparticles is capable of suppressing the production of space charges. Thermally stimulated currents in nanocomposites reveal strong correlation between the traps and electrical properties of nanocomposites. It is believed that this study would provide important hint for future studies of the interface mechanism in improving properties.