Abstract: Microst ructural characteristics and thermal shock resistance of nano-powder reinforcing Ti (C ,N) basedcermet s were investigated in order to efficiently improve the mechanical properties of Ti (C ,N) based cermet s and thehigh-speed cutting behaviors of cermet s cutters. SEM and TEM analyses show that the coarser ceramic particles exhibit a typical core-rim st ructure (core is usually referred to as TiC or Ti (C ,N) and rim is virtually a ( Ti ,Mo ,W)(C ,N) solid solution) . The nano-powder reinforcing mechanisms can be summarized as grain fining st rengthening ,dispersion st rengthening and solid solution st rengthening. The thermal shock test s on nano - powder reinforcingcermet s and conventional cermet s show that the quantity and size of the voids plus the size of micro-cracks in bothcermet s increase and other phenomena such as surface oxidation , cracks growth , cracks deflection and cracks bridging are found to become increasingly apparent with thermal shock cycles , and the nano-powder reinforcing cermet spossess a better thermal shock resistance in comparison with conventional cermet s.