Provided are a gas insulated switchgear (GIS) internal video monitoring system and a GIS internal video monitoring method. The GIS internal video monitoring system includes a GIS video sensor installed on a GIS enclosure and configured to acquire an open/close state of a GIS internal conductor in a real time manner, an intelligent power source module, a video server, and a video monitoring background system configured to control the intelligent power source module to supply power to the video sensor, where the GIS video sensor is connected with the video monitoring background system through the video server.