As the present of pulsed constant current source have problems of low amplitude and repetition frequency, we design a pulsed constant current source adopting integral feedback to get closed-loop current control, build the mathematical model and verify the function of the circuit by Pspice. The source adopts the working mode of energy storage and discharging with high-speed switch, uses MOSFET as linear adjustment switch and can be used for laser diodes loads. The maximum output current pulse is 600 A with adjustable pulse width from 100 μs to 600 μs, the largest output voltage is 320 V, the rising edge is under 40 μs and the maximum repetition frequency is 200 Hz. The structure of the source is compact, and the efficiency of the source can reach more than 90%.