The invention relates to an area backup automatic switch method and system. The method includes the steps that based on a series supply type wire-connected distribution network system, an area backup automatic switch function is configured on power distribution terminals in stations; bus voltages, on-off state information and fault isolation signals of the stations on a series supply circuit are collected through the power distribution terminals, and information interaction is performed between adjacent stations so that the stations can acquire the signal states of all the stations on the series supply circuit; after circuit faults are determined and reliably isolated according to the fault isolation signals, power supply of a non-fault area is restored according to the bus voltages and the on-off state information. Local equal configuration is adopted for the designed area backup automatic switch function, software and hardware installed on the stations are totally the same, a main station or sub-station system does not need to be depended on, the responding speed is at the second level, and power supply reliability can be effectively improved under the condition that no extra device is added.