Abstract: Experimental data of magnetic core under repeated magnetization, usually used during the design of high power pulsed equipment, can not accurately reflect its performance under pulsed magnetization. A method of magnetic core test and data processing under pulsed magnetization is given. The loss characteristics of a kind of glassy alloy magnetic core under pulsed magnetization are experimentally studied. The relationship between magnetic core loss and magnetization rates is presented. The saturation time ranges from 67 to 1 410 ns and the magnetization rate ranges from 1 to 40 T/s. The percentages of hysteresis loss and eddy loss are analyzed. The experimental results show that the relationship between magnetic core loss and magnetization rates accords with the saturation wave model. Moreover, the core loss is directly proportional to the magnetization rate.