The invention discloses a geographic information accessory system applicable to large screen, comprising a human-machine interface module, a dispatching control module, a video stream access module, a history database management module, a data restoring module, a static data management module and a SVG file analyzing module; wherein the human-machine interface module is used for providing dynamicscaling contouring display, control and legend panel and realizing hidden function; the dispatching control module is used for updating DXF base map data location mode, so as to display more plentiful information; the video stream access module is used for carrying out real-time monitoring on each user substation; the history database management module is used for storing history data and calculating the minimum and maximum of each record; the data restoring module is used for designing and implementing a time positioning function and providing history data inquiry function for the user; the static data management module is used for storing and managing static data; and the SVG file analyzing module is used for converting a circuit wiring diagram of power system into a high resolution vector pattern applicable to large screen. Besides, the invention also discloses an implementation method of the system. The invention can inquiry internal wiring diagram of the substation and video monitoring signal in real time, and operation is simple.