Since　SF6　has　a　very　high　global　warming　potential,　it　is　essential　to　replace　SF6　with　environmentally　friendly　insulation　gas.　However,　most　readily　available　insulation　gases　have　low　electrical　breakdown　strength,　which　needs　to　adopt　additional　insulating　means　to　enhance　the　poor　breakdown　strength.　In　this　paper,　with　the　aim　of　improving　breakdown　strength,　filler/epoxy　(EP)　composites　with　nano-SiO2　particles　in　the　weight　percentage　range　of　0-5　wt%　are　used　as　dielectric　coating　materials　and　N-2　is　applied　as　insulating　gas.　As　compared　to　that　of　neat　EP,　there　is　a　decline　in　permittivity　of　SiO2/EP　nanocomposites　in　the　frequency　range　from　10(-2)　to　10(6)　Hz.　Moreover,　for　SiO2/EP　nanocomposites,　the　permittivity　increases　at　first　and　then　decreases　as　the　filler　content　increases.　With　respect　to　the　gas-coating　insulation　system,　50%　breakdown　voltage　(BDV)　U50　of　the　electrode　with　pure　EP　dielectric　coating　material　is　larger　than　that　of　bare　electrode.　Furthermore,　a　better　BDV　performance　is　obtained　when　applying　SiO2/EP　nanocomposites　as　dielectric　coatings,　indicating　the　introduction　of　SiO2　nanoparticles　into　EP　matrix　can　reinforce　the　property　of　epoxy.　The　maximum　BDV　of　93　kV　occurs　in　the　electrode　with　3　wt%　SiO2/EP　coating　material,　which　is　29.17%　higher　than　that　of　bare　electrode.　Additionally,　it　is　found　that　the　permittivity　of　coating　material　has　a　significant　influence　on　the　breakdown　performance　since　it　can　alter　the　electric　field　distribution,　and　a　lower　permittivity　always　gives　rise　to　a　higher　BDV.