In view of the application requirements of the repetitive Marx-type pulse power source, a technology combining solid-state modulator and pulse transformer inductive adder was adopted to conduct research on high-power repetition-rate and high-voltage pulse charging power supply technology. The constant current charging technology based on BUCK-BOOST topology circuit was analyzed, and designs of key components such as high-voltage pulse transformer, pulse modulation module, BUCK-BOOST charging module, and control unit were provided. Finally a high-power repetitive pulse charging power supply prototype was developed. The prototype design specifications include a maximum output average power of 250 kW and a maximum repetition rate of 100 Hz. Charging tests were conducted on a 0.5 μF capacitive load, and an output pulse with a voltage of about 100 kV and a pulse rise time of about 300 μs was obtained. The pulse charging power supply adopts the design concept of multi module parallel connection in the primary design of the pulse transformer, which reduces the device volume and high voltage insulation risk. Under the conditions of high output power and high voltage, it achieves compact and modular design.