The pulsed power supply of semiconductor laser is studied in this paper. This paper adopts a Metal Oxide Semiconductor Field Effect Transistor as a switching device; applies a closed-loop feedback system, the use of negative feedback principle of constant current output. To prevent damage to the semiconductor laser due to overshoot voltage and ripple, a current-limiting protection circuit was added to the design of the circuit and a high slew rate op amp was used. After testing, the overshoot voltage is eliminated and the output of the pulse constant current is realized. The practical application indicates that the pulse constant current source driving circuit is safe and reliable to the laser with a peak power of up to 40W.