During the milling process of 6061 aluminum alloy, the tool is seriously worn and the machining efficiency is low, manufacturing quality is poor due to the severe thermal mechanical coupling of the cutting tools. The wear morphology of the tool was observed and analyzed by the VH-Z20W observing system and energy spectrum analysis (EDS). During the cutting process, the machined topography of the workpiece was observed, and the change of the workpiece shape with the tool wear is analyzed. The results show that when milling 6061 aluminum alloy with uncoated carbide tools, tiny chipping of the cutting tool is easy to occur at the beginning of milling. During the milling process, the diffusion has greater impact on the tool wear. In the early wear of the tool, the surface roughness of the workpiece is increased obviously, and the surface roughness of the workpiece is increased slowly when the wear amount increases uniformly.