In order to study the cutting performance and wear mechanism of nitrogen-silicon coated ceramic tools,TiAlN and CrAlN coatings were deposited on the surface of silicon nitride tool by physical vapor deposition（ PVD）.The tool life and wear mechanism were systematically studied by cutting gray cast iron HT200.Different depths of cut,feed rate and cutting speed were discussed.The wear condition of the lower tool,and pays attention to the optimal cutting speed of ceramic coated cast iron.The cutting performance of the tool under different cutting speeds is analyzed.The results show that the TiAlN and CrAlN coated tools can effectively improve the hardness of the tool.There is no obvious difference in the wear mechanism of gray cast iron.The wear mechanism is mainly abrasive wear.With the increase of cutting speed（ V,c,= 250 m/min ～ 450 m/min）,the cutting life of silicon nitride coated ceramic tools is rapidly reduced.Provide theoretical guidance for the development of nitrogen-silicon coated ceramic tools.