Abstract: As TC18 is difficult to machine, the cutting speed and tool life are the main obstructions to improve the production efficiency and manufacturing cost control when machining TC18. This paper presented the tool wear pattern and tool wear mechanism of milling TC18. The results show that in the same cutting parameters, the carbide tool with PVD coating (TiN+TiAlN) has longer tool life than uncoated tool, the wear pattern is cater for diffusion and adhesive in the rake face after coating desquamated; while the wear pattern of uncoated tool is tipping.