Structural　parameters　of　microchannel　heatsink　such　as　thickness　of　the　front　wall　and　width　of　the　turn-over　channel　are　optimized　through　numerical　calculation　based　on　general　industrial　processing.　And　copper　microchannel　heatsinks　are　fabricated　by　using　photophobia,　chemical　etch　and　diffusion　welding　technology.　Semiconductor　laser　bars,　with　cavity　length　of　1mm,　emitter　width　of　200μm　and　50%　of　fill-factors　are　packaged　on　the　presented　microchannel　heatsinks　and　tested.　With　an　exterior　size　of　27mm×11mm×1.5mm,　thermal　resistance　of　microchannel　heatsink　reaches　0.34K/W,　which　meets　the　need　of　cooling　of　high　power　semiconductor　laser　bars.