The dispersion and stability of PZT aqueous suspensions were investigated by using ammonium salt of polyacrylic acid (PMAA-NH4) as the dispersant. By observing the sedimentation behavior and measuring the viscosity, the effects of dispersant concentration and pH value on the dispersion and stability of the suspensions were studied. The experiment results showed that the optimum concentration of PMAA-NH4 and the optimum pH were 0.25-0.45 wt.%( by weight of the PZT powders) and 8.5-10, respectively. When the dispersant concentration was about 0.45 wt.%, and pH value was about 9.4, the stable PZT suspensions with high solids loading (up to 52 vol.%) and low viscosity (<1Pa.s) was obtained for gelcasting. The microstructure of ceramic formed by gelcasting was denser and more homogeneous than that by die pressing.