This paper presents a study on the electrothermal explosion of metallic powders produced by a pulsed high voltage generator, which is a fast-discharge capacitive storage device. The character of instantaneous current, voltage were measured and studied. The energy-utilization ratio was calculated and analyzed. It is shown that the maximum current density and current rise rate obtained during electrothermal explosion of Cu powder were of the order of 108A/cm2 and 1013A/s, respectively. The total energy deposited on exploding was 38.57%~65.90% of the total electrically stored energy, and increased with the charging voltage and powder masses exploding increasing. Meanwhile, the electrical energy applied to the powder was estimated to be about 1.5~2 times the energy theoretically required to vaporization of the powder and metallic exploding. And the energy input in exploding supplied by circuit increased with the charging voltage and the metallic powder conductor height increasing.