A　facile　method　using　a　nanocomposite　coating　is　proposed　to　suppress　surface　charge　accumulation　and　enhance　the　surface　breakdown　strength　of　polymeric　insulating　materials　like　epoxy　resin,　by　covering　a　thin　1,1,2,2-tetrahydroperfluorodecyltrimethoxysilane　modified　alumina　(Al2O3)　flake/UV　curable　resin　nanocomposite　coating.　Due　to　the　peculiar　characteristics　of　perfluorooctyl　chains　at　the　microscale　and　the　intricate　topographical　structure　of　morphology　at　the　mesoscale,　the　coating　exhibits　enhanced　water/oil　repellence,　surface　charge　accumulation　resistance,　and　flashover　withstanding　capability.　It　is　found　that　increasing　the　content　of　modified　Al2O3is　conducive　to　decreasing　the　surface　free　energy　of　the　specimens,　rendering　them　superhydrophobic.　Experimental　tests　in　air　show　that　the　presence　of　nanoparticles　generates　numerous　carrier　traps　at　the　surface　layer,　contributing　to　a　much　faster　charge　decay　rate.　Furthermore,　impulse　flashover　voltage　tests　under　vacuum　show　a　＞100%　improvement　of　surface　electrical　strength.　Further　experimental　results　reveal　that　lower　secondary　electron　emission　yield　remarkably　alleviates　the　surface　charging　phenomenon,　thus　relieving　electric　field　distortion　caused　by　hetero-charges.　We　envision　that　such　a　multifunctional　strategy　for　surface　discharge　mitigation　is　efficient,　adaptable　and　easy　to　scale　up,　and　thereby　exhibits　great　prospects　for　applications　in　electronics　and　electrical　power　systems.　©　The　Royal　Society　of　Chemistry　2020.