Abstract: Zirconia toughened alumina (ZTA) ceramic slurries with high solid phase content (45%-57%, volume fraction) and different pH (1-12) were prepared under different zirconia mass fractions (25.0%, 27.5%, 30.0%) and dispersant additions (0.2%-0.4%, mass fraction). The effects of pH, dispersant addition and solid phase content on the rheological properties of the ceramic slurries were studied. Ceramic slurries containing different amounts of zirconia were prepared at the optimum pH and dispersant addition, and were molded by aqueous gel-casting, and then sintered at 1 600 ℃ under atmospheric pressure. The relative density and mechanical properties of the sintered ceramics were tested. The results show that when pH was 7-12, the Zeta potential and viscosity of ZTA ceramic slurry first decreased and then increased with the increase of pH. At pH of 9, the absolute value of Zeta potential was the largest and the viscosity was the smallest, indicating that the ceramic slurry was most stable. With the increase of dispersant additions, the viscosity of the slurry first decreased and then increased. With the increase of solid phase contents, the viscosity of the slurry increased. High solid phase content (45%-55%) ZTA ceramic slurries with good fluidity and low viscosity were prepared under pH of 9 and dispersant mass fraction of 0.3%. The slurries prepared under this condition were molded and sintered, and the relative density, bending strength and fracture toughness of the sintered ceramics were relatively high when the solid phase content was relatively high.