Nano-scale ceramic materials are very suitable to be used as the high speed cutting tool owing to their excellent properties. The incorporation of nano-scale second phase, such as SiC and Ti(CxN1-x) particles, into a ceramic matrix can lead to an improvement in mechanical properties, which is contributed to a change in microstructure. However, the differences between nano-scale ceramic materials and monoclinic ceramic materials can be found through fabricating these two kinds of materials. Firstly the changes in microstructure that will affect the mechanical properties of the nano-scale ceramic materials are investigated as the nano-ceramic tools are compared with the monolithic ceramic tools. Secondly the effect of microstructure on the mechanical properties is discussed. Finally the microstructure formation mechanism of nano-ceramic materials is given on the bases of some hypotheses.