Circuit control system of boarding bridge, boarding bridge and emergency bridge withdrawing control method

The invention discloses a circuit control system of a boarding bridge, the boarding bridge and an emergency bridge withdrawing control method. The circuit control system comprises a PLC control loop, an emergency bridge removal control loop, an execution loop and a change-over switch. The PLC control loop comprises a PLC control chip and is used for outputting a control signal for a walking system of the boarding bridge; the emergency bridge withdrawing control loop comprises an emergency bridge withdrawing control module which is used for outputting an emergency bridge withdrawing control signal to the walking system; the execution loop acts on the walking system and works according to a control instruction for the walking system; the change-over switch comprises a first connection state and a second connection state. Wherein when the change-over switch is in a first connection state, the PLC control loop and the execution loop are conducted; and when the change-over switch is in the second connection state,