This paper introduces the design of high pulsed power supply system for producing pulsed high magnetic field up to 70 T.This system consists of 58 sets of 55 μF of capacitor bank which provides 1.0 MJ energy storage.A set of vacuum closing switch is chosen as main switch for energy discharge into magnetic coil.A crowbar circuit with high power diodes in series with resistor is used to absorb the redundant energy and adjust pulse width.The resistance of magnetic coil changing with current is deduced by energy balance equations.A capacitor-charging power supply using a series-resonant

constant on-time variable frequency control

and zero-current switching charges the capacitor bank in one minute time with high efficiency.The pulsed power supply provides adjustable current and pulse width with 30 kA peak and 30 ms maximum.The primary experiments demonstrate the system reliability.This work provides an engineering guidance for future development of pulsed high magnetic field.