Ti6Al4V is a difficult to machine alloy with low cutting efficiency and server tool wear. A series of orthogonal turning tests with CBN (Cubic Boron Nitride) in higher speed scale was carried out on a CA6140 lathe. The experiential functions of tool life based on orthogonal experiment were developed. The tool wear morphologies were examined by scanning electron microscope (SEM) and energy disperse spectroscopy (EDS), adhesion, diffusion and micro-chipping were the major wear mechanisms of CBN tool. Finally, the cutting parameters of CBN tool in Ti6Al4V dry turning were optimized based on tool life-efficiency contour analysis, in same cutting efficiency, the higher cutting speed and small depth of cut are the better selection, it means that utilization of CBN tool enables the high cutting speed turning of Ti6Al4V.