Abstract: FeCuNbSiB multilayered flims are prepared by radio frequency（RF）sputtering.The as-cast sample has a maximum GMI ratio of 44.3% at 12MHz.Complex permeability and equivalent circuits are used to demonstrate the magnetization processes,which are relevant to GMI effect.DC applied field is to produce a damping in domain wall movements,which is responsible for the minus parallel RL arm in equivalent cirCuits.The relaxation frequency of the sample is about 12MHz,near which the maximum GMI happens.