Corona　and　spark　are　two　typical　discharge　types　in　gas-insulated　switchgear　(GIS).　Studies　on　the　SF6　decomposition　characteristics　under　corona　and　spark　are　significant　for　the　safe　operation　of　the　GIS.　In　this　paper,　the　discharge　energy/charge　and　SF6　decomposition　products　under　ac　corona　with　point-to-plane　electrode　defect　and　spark　with　floating　potential　defect　were　investigated　under　different　electrode　dimensions,　applied　voltages,　SF6　gas　pressures,　adsorbents　and　moisture　contents.　The　upper　limit　of　the　formation　rates,　feature　extraction,　and　the　amount　of　wear　of　the　GIS　were　also　discussed.　The　results　show　that　the　influences　of　gas　pressure　and　moisture　content　on　the　discharge　energy　and　SF6　decomposition　products　under　two　different　defects　are　distinguishable.　In　addition,　the　concentration　ratios　of　(SOF2+SO2)/(SO2F2)　under　corona　and　spark　lie　in　the　ranges,　0-1,　and　1-5,　respectively.　The　formation　rates　of　SF6　decomposition　products　calculated　from　experimental　results　under　corona　discharge　lie　in　the　range,　0.1-5　mu　moles/J.　However,　the　formation　rates　under　spark　are　usually　in　the　range,　0.02-0.04　mu　moles/J,　which　are　far　lower　than　that　under　corona.　Theoretically　the　upper　limit　of　the　formation　rates　under　corona　and　spark　are　estimated　to　be　in　the　ranges,　67-540　mu　moles/J,　and　188-376　nmoles/J　respectively.　Besides,　the　concentration　ratios　and　formation　rates　can　be　used　to　distinguish　the　discharge　types　and　the　amount　of　wear　of　the　GIS　can　be　estimated.