Disclosed is a standby-power-supply automatic switching device system. The standby-power-supply automatic switching device system which is high in security, capable of automatically judging bus faults and executing corresponding action strategies according to positions of fault points, isolating faults and restoring power supply is provided. The system includes an inlet wire M, an inlet wire N, a busbar, a standby-power-supply automatic switching device and a segmented combination unit. The inlet wire M and the inlet wire N are respectively connected with the busbar. The busbar is connected with the segmented combination unit. The segmented combination unit is connected with an acquisition plate. The acquisition plate is connected with a protective plate and a management plate. An applicable operating method of an inlet wire spare power automatic switching device LBZT1 is as follows: standby application of the inlet wire M, operation of the inlet wire N and operation of a section switch; and an applicable operating method of a segmented spare power automatic switching device FBZT is as follows: operation of the inlet wire M, operation of the inlet wire N and standby application of the section switch. The system improves device security and capable of restoring power supply.