Si₃N₄ powders have been pre-treated by shock activating and hot-pressed into Si₃N₄ ceramics. Three kinds of shock pressure, and three different sintering temperatures are used in the experiments, SEM, TEM and X-ray Diffraction have been used to analysis the structure of the Si₃N₄ powders and ceramics. The properties of Si₃N₄ ceramic have been tested. The results show that shock activation give positive action to the densification of Si₃N₄ powder and the increase of properties of the Si₃N₄ ceramics; the ceramic parts shocked under 40 GPa and sintered under 1800℃ have the best properties. The bend strength reaches 1107.2 MPa, at the same time, the fracture toughness reaches 12. 20MPa.m^1/2.