In order to study the wear and selection of different materials cutting tools in high speed milling of 7075 aluminum alloy， micro （MCD）/nano （NCD） diamond coated tools were prepared by chemical vapor deposition.The surface morphology of the film was observed by field emission scanning electron microscopy.Analysis of the structure and composition of CVD diamond coated tool films were analyzed by Raman spectroscopy.The same size cemented carbide cutting tool and MCD coated cutting tool were used to carry out rough machining high-speed milling experiment under the condition of dry cutting without lubrication.The wear condition of the two kinds of cutting tools after machining a certain distance was observed.In order to observe and analyze the surface roughness of the workpiece after finish milling，the same size cemented carbide tools，MCD coated tools and NCD coated tools were used to finish high-speed milling experiments under the condition of dry cutting without lubrication.The results show that the life of MCD coated tool is three times longer than that of cemented carbide tool when milling 7075 aluminum alloy with large depth and high speed.In the high-speed finish machining of 7075 aluminum alloy with small cutting depth and large feed，the average surface roughness of the workpiece milled by three kinds of cutting tools is 0.981 μm，1.122 μm and 0.960 μm.The machining effect of NCD coated tool is better than that of MCD coated tool.At the same time，through the comparison of rough and finish machining experiments of the same material tool，it is found that the life of the same specification tool in small cutting depth and large feed high-speed finish machining is ten times of that in large cutting depth and large feed high-speed rough machining.The results show that MCD coated tool is the best for rough milling and ncd coated tool is the best for finish milling of 7075 aluminum alloy.