Abstract: A fast pulsed power supply is developed to meet the requirements of High Intensity heavy-ion Accelerator Facility (HIAF) ion source. Based on front-stage voltage fast switching method, we proposed a circuit topology ensuring fast rising of current and flat top stability. In this paper the circuit is analyzed, the essential parameters of the circuit are calculated, and the control method is established for adapting abruptly-changed voltage. A 16 kW power supply based on the principle of modular manufacturing was tested on real magnet load. The results show the value of flat top current reaches 570 A, the error is less than ±1×10⁻⁴, the repetition frequency reaches 3 Hz, the rise time and fall time is less than 30 ms, the flat top time can be set within 900 ms.