Abstract: The transient characteristics of the doubly-fed fan are polymorphic and different from the traditional synchronous machine, and the short circuit current frequency of the doubly-fed fan contains a large proportion of the decaying speed frequency component, which makes it difficult to distinguish the faults inside and outside the transmission line area, meanwhile, the traditional protection is prone to mis-operation and non-operation; therefore, a pilot protection method for outgoing line of DFIG wind farm based on high-frequency impedance sudden variable is proposed. First, combined with the topology of the doubly-fed wind farm, the difference of the voltage amplitude and phase angle of the fan terminals on the collector line is taken into account, the short-circuit current of the doubly-fed wind farm is obtained, and the high-frequency component is extracted to construct the fault high-frequency model of the doubly-fed wind farm. On this basis, the high-frequency sudden variable network of the transmission line of the doubly-fed wind farm is constructed, and the high-frequency impedance measured by the protection on both sides of the transmission line is derived, and the protection criterion is constructed by using the impedance difference measured inside and outside the high-frequency sudden variable network area. Finally, the RT-LAB platform is used to simulate and verify that the proposed method can accurately identify the faults in and out of the zone and that real-time synchronization of information is not required at both ends of the line.