The microstructure and properties of a SiC particle reinforced and toughened siliconnitridebase matrix ceramic cuttingtool material have been investigated.The results show that this material has excellent mechanical properties.By adding the SiC particles,strength,toughness and hardness can be greatly improved,as compared with those of the pure siliconnitride ceramic.Microstructural analysis shows that the SiC particles prevents the grain growth of Si\-3N\-4,and also improves the microstructure of Si\-3N\-4base ceramic.The toughening mechanism of SiC in the Si\-3N\-4 matrix is also discussed.