In this paper, a cascade high voltage microsecond pulse power supply with output voltage of 20 kV is developed. The voltage level of a single module is 500 V, which reduces the insulation withstand high voltage requirements of the device. The output voltage value range of this pulse power supply is 0-20 kV ; the repetition frequency is adjustable between 0-10 kHz; the pulse width is adjustable between 0-30 μs; the output current value is between 0-15 A; the rising and falling edge of the power supply are all within 1μs. Modular design improves the redundancy fault tolerance of this power supply and reduces its failure rate. When this power source is used as an excitation source for plasma production, and the output high voltage pulse waveform is stable, the power supply can be conveniently adjusted according to different load. When the voltage and frequency change, the mode of the discharge is different.