Long -range access control system of transformer substation, including the centralized control platform, the centralized control platform passes through the wire and connects transmission control unit, and transmission control unit passes through wireless connectivity sub -station intelligent key, transmission control unit includes the portal frame, the upper portion monitoring device device of portal frame, and two automatic push -and -pull doors of lower part installation of portal frame, two automatic push -and -pull doors are installed respectively in the both sides of portal frame, an installation shelves pole on one of them automatic push -and -pull door, the one end of shelves pole is articulated with automatic push -and -pull door. The utility model discloses a centralized control platform can carry out real time control to transmission control unit's running state. The utility model discloses a transmission control unit can open and close automatic push -and -pull door according to sub -station intelligent key outgoing letter automatic control under unmanned on duty's the condition.