In order to study the effect of process parameters on the surface roughness of CuCrZr alloy micro-channel formed by selective laser melting (SLM) technology, CuCrZr alloy sample with micro channel was prepared by orthogonal experiment. The roughness and micro morphology of the inner surface of the sample were measured by 3-D topography instrument and scanning electron microscope. The effects of laser power, scan speed and hatch distance on the surface roughness of the overhang surface and side surface of the microchannel were analyzed. The results show that the scan speed has the greatest influence on the roughness of the overhang and side surfaces, and the overhang surface is affected by the quality of the molten pool itself, resulting in the phenomenon of “slag hanging”; while the side surface roughness is greatly affected by the Marangoni effect. After optimization, under the process parameters of laser power 380 W, scan speed 520 mm/s, and hatch distance 0.12 mm, micro-channel samples with minimum side surface roughness (16.91 μm) can be processed; laser power is 320 W, scan speed is 560 mm/s, under the process parameters of 0.14 mm hatch distance, the micro-channel sample with the smallest overhang surface roughness (24.86 μm) was obtained. This research provides the basis for SLM forming surface precision from the perspective of laser processing window, and gives the preliminary process parameter scheme.