Rotor steel 26NiCrMoV145 has been widely employed in aerospace and power industry because of its unique properties. As to this new material that used widely in important places, it is worth studying its machinability. An experiment was carried out to study the cutting forces and tool wear mechanism during high speed dry turning using multilayer Al2O3 coated carbide insert. The orthogonal test was chosen, cutting forces were measured. SEM analysis has been carried out on worn tools to determine the tool wear mechanisms. Crater wear and coating peeling could be found in every cutting speed. Flank face wear appears smooth when cutting speed increases. At last, an optimization of the cutting condition was suggested when considering of material remove rate, cutting forces and tool wear.