Light supplementing device and method for monitoring on-off state of GIS disconnecting switch contact

The invention relates to the field of high-voltage switch equipment in an electric power system, in particular to a light supplementing device and method for monitoring the on-off state of a GIS disconnecting switch contact. The device comprises a remote observation window and a visual observation window of a GIS disconnecting switch; a light guide part which is detachably connected to the remote observation window; a light source which is detachably connected to the light guide part, and is diffused into the GIS disconnecting switch through the light guide part; and a linked switch which is linked with the visual observation window, and is electrically connected with the light source. According to the invention, a polaroid is adopted as a medium for an LED lamp light source to enter the GIS disconnecting switch, so that the problem that the light source can reflect light spots on the remote observation window glass and a contact metal shielding cover is effectively solved, the scattering area of the light so