To improve the heat management of high-power diode lasers, a microchannel heat sink is obtained, whose structure is optimized in method of numerical simulation. Following such a design, the microchannel heat sink is fabricated by nickel-based doping rare earth materials by laser three-dimensional (3-D) printing procedure. Since the noncorrosion property of such material has been preliminarily demonstrated by salt spray test, there is no necessity to plate the interior of the laser 3-D printing microchannel heat sink with gold. The coefficient of thermal expansion of such material is 11 ppm/K. The diode laser array (LDA) with 80-W cw output power, 2-mm cavity length, 100-μm emitter width, and 20% fill-factors is mounted on it for the thermal resistance test, and the result is 0.40 K/W. Moreover, the smile effect of the mounted LDA is merely 0.8 μm.