Exposure　to　corona　discharge　damages　the　polymeric　structure　of　alumina　trihydrate　(ATH)　filled　silicone　rubber　composite　insulators.　In　this　work,　an　attempt　has　been　made　to　enhance　the　resistance　against　sustained　long　term　corona　exposure　of　ATH　filled　silicone　rubber　by　fabricating　its　co-filled　composites　through　addition　of　a　small　amount　of　nano　Al2O3.　Fabricated　specimens　comprise　a　pristine　sample　of　silicone　rubber　(SR),　one　micro　{40wt%　ATH　(MSR)}　composite　and　two　co-filled　{39wt%　ATH+lwt%　nano　Al2O3　(MSR1%)　and　38wt%　ATH+2wt%　nano　Al2O3　(MSR2%)}　composites　with　total　particle　loading　of　40wt%.　They　are　subjected　to　AC　corona　exposure　produced　from　a　needle　electrode　tip　for　seven　days.　Performance　evaluation　is　achieved　through　SEM　(Scanning　electron　microscopy),　FTIR　(Fourier　transform　infrared　spectroscopy),　hydrophobicity,　and　surface　roughness.　Test　results　show　severe　material　ruptures　occurred　in　SR　but　damage　in　the　form　of　pits　and　voids　in　MSR　and　MSR1%　in　the　area　directly　below　the　needle　tip.　Interestingly,　MSR2%　exhibits　subdued　damage　and　a　compact　lump　structure.　The　hydrophobicity　recovery　rate　is　significantly　higher　below　the　needle　tip　than　in　the　vicinity,　and　in　the　SR　as　compared　to　the　other　composites.　Also　noted　is　higher　increment　in　average　and　peak　surface　roughness　below　needle　tip,　and　strong　resistance　to　roughness　increment　by　MSR2%.　FTIR　results　show　higher　concentration　of　hydroxylation　and　aluminum　nitrites　in　MSR　and　the　absorbance　intensities　of　principal　functional　groups　show　fewer　deviations　in　MSR1%　and　MSR2%　relative　to　their　virgin　states.　Based　on　experimental　results,　it　is　concluded　that　corona　resistance　of　micro　ATH　filled　silicone　rubber　can　be　enhanced　through　addition　of　small　amount　of　Al2O3　by　fabrication　of　co-filled　composites.