Abstract: The series parallel characteristics of AC-Link series resonant high voltage charging power supply are studied, the difference in parameter of a power supply module and the synchronization of multiple modules series-parallel characteristics are analyzed, and the results show that the difference in parameter of a power supply module and synchronization has no effect on power supply in parallel characteristics. In series mode, power supply module parameter difference, lead to the different average output current, with the extension of charging time, the series output voltage difference will greater, output voltage difference do not change with the charging time with different synchronization time . Developed two charging rate 30 kJ/s, the output voltage 30 kV high voltage charging power supply for experiment, the experimental results show that: charging power supply can work in parallel and series mode, series mode for 60 kV output voltage, power supply module output voltage difference is less than 2.5% of the load voltage.