The invention discloses a remote access control system for a substation. The remote access control system comprises a centralized control platform, wherein the centralized control platform is connected with a transmission control device through a conducting wire; the transmission control device is connected with an intelligent key of the substation through a wireless signal; the transmission control device comprises a portal frame; the upper part of the portal frame is provided with a monitoring device, and the lower part of the portal frame is provided with two automatic sliding doors; the two automatic sliding doors are respectively arranged at two sides of the portal frame; one of the automatic sliding doors is provided with a selector rod; and one end of the selector rod is hinged with the automatic sliding door. The centralized control platform of the remote access control system can be used for controlling the operation state of the transmission control device in real time. The transmission control device can be used for automatically controlling the automatic sliding doors to be opened or closed under an unattended condition according to a signal emitted by the intelligent key of the substation.