Abstract: The properties of several materials as explosive emission cathode were studied experimentally on high voltage (0.6~1.0 MV), repetitive (100 Hz) electron accelerator, such as effective emission area, average current density, diode impedance and energy losses of electron beam. The results show that the effective emission area varies with the applied diode voltage just like square wave response. The effective emission area varies mildly 5 ns after the voltage pulse beginning. Among carbon fiber, velvet, graphite and stainless steel, the carbon fiber has the largest effective emission area and average current density. The diode impedance increases linearly with the increase of the cathode-anode gap distance. The diode impedance mismatch with the transmitting line is the main factor of the ener