Abstract: To study the characteristics of gaseous discharge in spark gap, a high-voltage pulsed power supply has been designed, whose output voltage amplitude varies between 30～100 kV and repetition-rate varies from 1 Hz to 5 kHz. Adopting the principle of resonant charging, the power supply transferrs energy from the primary source of 10 kV DC to the secondary energy storage capacitor that is charged at least to 18 kV. The hydrogen thyratron conducts under the action of optical trigger signal. Then the current flows through the pulse transformer, and voltage is raises from 18 kV to the peak of 100 kV. The output pulse is a negative voltage one with an pulse width of at least 200ns. and fall timeless than 90 ns. The device can continuously run for no less than 1 min without additional cooling system.