Generally, the machinability of materials that have a good mechanical properties is poor. For materials having a high strength, high toughness, high strength in high temperature and wear resistance, it is difficult to remove a chip from work material. Nickel is a kind of these materials, so this metal can be used in many industrial fields. But it is limitted in use because of high cost and poor machinability. In this study, the cutting of pure Nickel was conducted to examine wear of CBN, poly crystal diamond and single crystal diamond tools. From the results, the CBN tool is superior to poly crystal diamond tools or single crystal diamond tools in terms of tool wear. And the influence of cutting parameters on tool wear was examined by mathematical modelling that contain a 2th least square interpolation.