A compact series resonant high voltage capacitor charging power supply with an average charging power of 12 kW is developed based on full bridge series resonant constant current charging technology to meet the repetitive charging requirement of a high power pulsed generator. The power supply uses supercapacitor pre-storage and full-bridge series resonant circuit, which greatly reduces the demand for environmental power supply. Combining with modular integrated design, the integrated and portable design is realized. According to the working requirement of the pulsed power generator, this paper analyses the basic principle and working process of the full bridge series resonant circuit, presents the design method of circuit parameters and the circuit simulation results. The power supply developed was used to charge a PFL-Marx pulsed power generator with the equivalent capacitance of 0.3 μF, the charging voltage was more than 60 kV in 45 ms. The experimental results show that its output capacity meets 20 Hz repetitive charging requirement of the PFL-Marx pulsed power generator.