Glass fiber reinforced epoxy nanocomposites were synthesized with different weight percentages of MgO nanofillers. The experimental procedures adopted for synthesis of nanocomposites have ensured the uniform dispersion of nanofillers. The influence of nanofiller additions on mechanical and electrical properties of nanocomposites, especially for aerospace and high voltage insulation structures have been investigated. The mechanisms governing the improvement in electrical, thermal and mechanical properties of the composite observed would be discussed in detail.