In　gas　insulated　switchgear　(GIS)　substation,　due　to　the　operation　of　disconnect　switch　and　circuit　breaker,　as　well　as　short-circuit　fault,　SF6　will　break　down　very　rapidly.　The　superposition　of　refraction　and　reflection　of　high-frequency　travelling　waves　will　cause　the　very　fast　transient　electromagnetic　pulse　(EMP).　High-frequency　EMP　propagating　along　GIS　core　wire　will　couple　to　GIS　enclosure　which　forms　transient　enclosure　voltage　(TEV).　Through　the　study　of　new　GIS　enclosure　coupling　model　which　can　be　verified　by　site　test　and　frequency　effect　on　the　enclosure　coupling　under　high-frequency　EMP,　results　indicate　the　generation　of　TEV　is　closely　related　to　GIS　structures　and　the　electromagnetic　wave　propagation　characteristics　on　its　core　wire　and　enclosure.　Electromagnetic　coupling　model　must　consider　the　entire　propagating　and　coupling　process　of　EMP　in　GIS.　Paper　also　shows　that　TEV　is　mainly　formed　by　high　frequency　＞0.1　MHz　EMP　coupling　and　the　difference　on　coupling　extent　when　frequency　is　＞1　MHz　is　small.　©　2019　Institution　of　Engineering　and　Technology.All　right　reserved.