The utility model belongs to the technical field of power equipment, concretely relates to rain -proof cover of GIS benzvalene form insulator. The utility model discloses it does not have the protection casing mainly to solve GIS benzvalene form insulator, leads to the insulator to split and damage easily, pours partial gap and easily intakes, produces the problem that gas leakage caused the equipment accident. The utility model relates to a rain -proof cover of GIS benzvalene form insulator, including rain -proof cover body, rain -proof cover body be semi -circular, be provided with an arc flexible connecting portion spare respectively at the both ends of controlling of rain -proof cover body, two arc flexible connecting portion spares the same with the radius of rain -proof cover body, every arc flexible connecting portion spare all is that the outside makes arc flexible connecting portion spare outwards to expand with rain -proof cover body is articulated.