High-power fiber laser cutting of AA2219 aluminum alloy was studied. The cutting surface morphologies were examined by optical stereoscopic microscope, and the characteristic sizes were measured by a Vernier caliper. The results showed that the cutting surface was grouped into three zones featured by different striation patterns from the upper to the bottom, which are horizontal striation zone at the upper, vertical striation zone at the middle, and oblique striation zone at the lower. The oblique striation zone was the roughest zone. An optimal range of laser line energy to get an accepted cutting surface both with a small fraction of oblique striation zone and less dross was found, which was determined as 25–35 J/mm. The formation mechanisms of surface features were summarized by the interaction between the gas flow inside the cut and the forces exerted on the molten pool.