Abstract: Preheated explosive consolidation (PHEC) experiments were performed on the -Al2O3 nanometer ceramic powders under different explosive pressures at the preheated temperature of about 0.5Tm. The crystal types for the studied ceramic powders were analyzed by using the X-ray diffraction data, and their microstructures were observed with a high-resolution scanning electronic microscope. The experimental results show as followings: (1)when the shock pressure reaches 13.1 GPa, the -Al2O3 nanometer powders are well sintered to -Al2O3 crystal type; (2)the crystal grains in the sintered bulk are combined tightly with each other and the average grain size is around 100 nm, but the -Al2O3nanometer powders cannot be changed into -Al2O3 crystal type when the shock pressure decreases to 9.35 GPa.