The invention provides a system and a method for controlling an automatic backup power switching device of a transformer substation. The system comprises a plurality of transformer substation systems and a transformer substation automatic backup power switching device master station, wherein the transformer substation automatic backup power switching device master station is respectively connected with the plurality of transformer substation systems and used for monitoring operating data of the plurality of transformer substation systems in real time; when the power supply capacity of at least one of the transformer substation systems is insufficient, the transformer substation automatic backup power switching device master station is used for controlling the automatic backup power switching device in each transformer substation system to enter or exit according to operating data of each transformer substation, obtained by monitoring. Therefore, the transformer substation systems are respectively in communication connection with the transformer substation automatic backup power switching device master station to form the local power grid power supply capacity-based system for controlling the transformer substation automatic backup power switching device; by utilizing the system and the method disclosed by the invention, the intelligent entrance or exit control on the automatic backup power switching devices in all the transformer substation systems in the local power grid can be realized; by comprehensively considering the bearing capacity of the power grid, the reliability of power supply of the power grid is improved.