A design method for a high-power laser diode array power supply is introduced. The structure, component and working principle of the proposed power supply are analyzed as well as the influencing factors on the output current pulse rise time. The structure of output cable and the sampling circuit are optimized. The output current pulse rise time is greatly shortened under the high-current and long-distance conditions. The testing results verify the feasiblity of the power design idea. The high-power laser diode array power supply features a continuous adjustable laser dirving current of 0-300 A，and the stability of output current achieves 0.3%. The output current pulse rise time is 24.7 μs given the current of 300 A and the output cable length of 40 m. It provides reference for the same type of designs and a basis for engineering applications.