Abstract: Blast furnace slag is an industrial waste slag produced by ironmaking blast furnace, which contains silicate components such as CaO, Al₂O₃, SiO₂ and a small amount of crystallization nucleating agents such as Fe₂O₃, TiO₂, ZrO₂. After it was heat treated at 855 ℃ for 1 h, the crystal phase of Ca₂Al₂SiO₇ about 1μm could be nucleated and crystallized, which indicates that blast furnace slag has high crystallization activity. Adding 4% of blast furnace slag to ZTA, the mechanical properties of ZTA ceramics are significantly improved at low temperatures after sintered at 1 550 ℃ for 30 min. Flexural strength and fracture toughness are 650 MPa and 6.03 MPa·m^1/2, respectively. There are 15% and 14.2% higher than that at the same sintering temperature without addition of blast furnae slag, and the sintering temperature is reduced by more than 50 ℃. The grain-refining furnace slag incorporated ZTA ceramic matrix, the liquid phase produces by blast furnace slag during the sintering process, which promotes the growth of Al₂O₃ rod crystal, the rod crystal extraction and crack deflection during the process of stress are conducive to the improvement of the mechanical properties of ZTA ceramics. The crystallization of blast furnace slag at high temperature enhances the grain boundary strength of ZTA ceramics and further improves the mechanical properties of the materials.