The invention discloses a parallel generator circuit breaker which comprises a current-carrying loop and a disconnecting loop connected with the current-carrying loop in parallel. When a short-circuit fault occurs, the current-carrying loop acts fast to form an arching fracture, fault currents are transferred to the disconnecting loop by using fracture arc voltages, and the disconnecting loop is used for enabling the fault currents to be directly disconnected or fast limiting the currents and then achieving the disconnection of the fault currents. A load switching unit with connecting resistance of tens of microhms is arranged in the current-carrying loop, more than 90 percent of the rated currents of the system can pass through the load switching unit, and heat loss on a GCN device in rated working conditions is reduced. Meanwhile, the current-carrying loop has a fast action capability, and normally disconnection to a full gate distance within two working frequency cycles after the occurrence of the fault can be selected. It can be ensured that the current-carrying loop has high arching voltages after a contact is turned on, and the fault currents are made to be transferred fast.