To meet the demands of small-caliber electromagnetic launch (EML) systems, which require high-amplitude, millisecond-duration pulse currents with fast rise times and flat-top waveform characteristics, a capacitor-based pulse power supply (PPS) was developed. The system has an energy storage capacity of 600 kJ and a maximum operating voltage of 8.4 kV. It adopts a modular cabinet structure comprising a power distribution unit, control unit, high-voltage charging unit, primary protection unit, and ten 60 kJ pulse power modules (PPMs). Each module achieves an energy density of approximately 0.81 MJ/m3 and a maximum short-circuit discharge current of 73kA. A synchronized encoded signal is employed to control the precise timing of the PPM discharges, while the high-voltage charging system uses a constant-current charging circuit based on a series resonant converter. The primary protection unit provides real-time voltage monitoring for all ten modules and offers enhanced system safety. Performance testing on a simulated load, as well as subsequent launch experiments, demonstrated that the PPS delivers flexible, reliable, and high-performance current outputs, effectively meeting the operational requirements of EML applications.