A design scheme is put forward according to the characteristic of high-repetition high-voltage nanosecond output wave and the operation characteristic of Semiconductor Open Switch(SOS), which generates special pulse wave by SOS. The operation process of the circuit is analyzed. Parameters of some important components in generator which can output 50 kV/100 Ω, 10 ns-20 ns and 100 kHz pulse wave are computed. Through analyzing the requirements on some important components including SOS, saturated transformer and subsidiary switch, an advice is presented on how to select these important components.