The invention discloses a method for rapidly restoring system power supply. The method comprises the following steps of: dividing reclosing delay into two times of delay 1 and delay 2 and respectively timing by a reclosing function module; judging the two times in parallel to achieve rapid reclosing, and sending a reclosing command to a starting automatic switching module; judging system fault and running condition by the starting automatic switching module, and sending a starting automatic switching command to the automatic switching module after reclosing failure is judged; and directly starting an automatic switching logic without delay matching after the automatic switching module receives the starting automatic switching command, closing a stand-by power supply and rapidly restoring system power supply. The invention also discloses a device for rapidly restoring system power supply. By the method and the device, rapid reclosing can be achieved after a fault in power grid occurs and a switch trips, and the success rate of reclosing is improved. The automatic switching module is directly started after reclosing failure is judged so as to rapidly restore system power supply.