Method for quickly switching back-up power supply network of urban rail transit to recover power supply

The invention provides a method for quickly switching in a backup power supply network of urban rail transit to restore power supply, which comprises the following steps of: S1, continuously judging whether external power introduction of a normal power supply looped network is completely powered off or not, if so, skipping to step S2, and if not, skipping to step S2; s2, simultaneously performing the following operations: starting and completing synchronization of the emergency diesel generator system, simultaneously closing all circuit breakers on the emergency power supply ring network segment A, simultaneously closing all circuit breakers on the emergency power supply ring network segment B, and if the operations are successful, skipping to the step S3; s3, closing a circuit breaker of the boost substation; s4, judging whether the bus on the equipment side in the substation of each station has voltage or not, and skipping to the step S5 for the station with voltage; and S5, closing the circuit breaker of t