Abstract: A primary unit was designed for high-repetition-frequency pulsed power generators based on semiconductor opening switches at tens of kHz. The low frequency circuit in the primary unit was optimized, including that the series and parallel modules of IGBT were adopted as discharge switches, the high frequency synchronized trigger generator was used to control operation of IGBTs, and the current feedback circuit was added. The experimental results indicate that residual voltage of the discharge capacitor after discharging of the primary unit could impact the output stability of the pulse generator, and such primary unit reinforces the stability and reliability of the developed high-frequency pulsed power generator at tens of kHz. According to experimental waveforms, the operating voltage is 1 kV and current is 1.5 kA, the primary unit could operate stably at 10 kHz.