Effects of TiAlN coating conditions on the cutting characteristics during machining high hardened tool steel using coated ball end mill were studied in this research. KP4 steel and STD 11 steel were used as workpieces. Minimum quantity lubrication (MQL) was utilized in the cutting. Scanning electron microscope, optical tool, and a tool dynamometer were used to measure coating thickness and progress of tool wear. Results showed that the cutting distance using TiAlN coated ball end mills was longer than that using WC-Co ball end mill by 2.3~5.7 times for KP4 steels and about 2.5~4.3 times for STD11 heat treated steels. The multi layer TiAlN coated ball end mill showed better performance of machining of hard steels than single layered coated tools.