Abstract: Based on the experimental data, this paper presents the pulsed magnetization characteristic of magnetic cores made of 25 μm metglass 2605TCA, 25 μm metglass 2605SA1 and 50 μm electric steel DG6. The characteristic parameter, the slope of the voltage pulse per unit area of magnetic core, is proposed to standardize the condition of exciting the core. It indicates that the magnetic flux density swing (ΔB) keeps nearly constant as the parameter is changed, the ΔB values of 2605TCA and DG6 are about 3.1 T, while the ΔB value of 2605SA1 is only 2.4 T. When the characteristic parameter is increased from 67 to 129, the relative permeability of 2605SA1 is decreased from 1800 to 1200, while the relative permeability of 2605TCA is decreased from 1100 to 400. Hence, the relative permeability of metglass varies evidently as the characteristic parameter is different. The DG6 performs not well under fast rise time pulse, which shows that the maximum of the relative permeability is only 130 and the relative permeability drops sharply as the magnetic core tends to be saturated. These experimental results are useful to the choice of the magnetic cores for fast linear transformer driver stage.