Abstract: A model based on the multilayer lossy transmission line was set up for studying induction accelerator cavity with ferrite cores. Experiments in short pulse exciting in both 5 kV and 220 kV voltages and simulations by PSpice were used to prove the model, and the average permeability and permittivity of the core during the pulses were calculated. The experiment and simulation results show that the model can describe the dynamic physical characteristics of the induction cavity with ferrite cores accurately, and the model makes it easier and more efficient to ananlyze the waveforms, to optimize the device and to sclect the magnetic cores of the induction accelerator cavity.