| Stability of aqueous barium strontium titanate suspensions (Ba0.6Sr0.4TiO3) was investigated with poly(methacrylic acid)(PMAA-NH4) as the dispersant. The average particle size of Ba0.6Sr0.4TiO3 was 2.03μm, which was prepared by chemical coprecipitation method, and its BET was 15.32m2/g. In 1vol% Ba0.6Sr0.4TiO3 suspensions, saturation adsorption of PMAA-NH4 on the Ba0.6Sr0.4TiO3 particle surface was 92.97mg/g in theory, according to Langmuir isothermal adsorption equation. The amount of PMAA-NH4 adsorbed on the surface of particles increased to saturation adsorption by increasing the concentration of PMAA-NH4 in the system to a certain degree. When the initial concentration of PMAA-NH4 got to 0.8wt% and pH values was between 8～9, saturation adsorption was presented and the suspensions maintained stable. The average particle size of Ba0.6Sr0.4TiO3, which was prepared by solid method, was 2.87μm, and its BET was 3.43 m2/g. Saturation adsorption of PMAA-NH4 was 5.86mg/g in theory with 5vol% Ba0.6Sr0.4TiO3 suspensions. When the initial concentration of PMAA-NH4 got to 0.4wt% and pH values was between 8～9, saturation adsorption was presented and the suspensions maintained stable. With the same initial concentration of PMAA-NH4, adsorption of PMAA-NH4 reduced as the pH values increased. The model of PMAA-NH4 adsorbed on the Ba0.6Sr0.4TiO3 particle surface was created, as function of pH values.Ba0.6Sr0.4TiO3-MgO composite powders were prepared by liquid-phase cladding process, and the property of the composite powders were discussed. The surface of the precursor was observed by SEM, and the packaging layer of MgO-BSTO composites is regularly homogenous. The precursor was calcined at 600℃for 2 hours. The crystall of MgO, as the packaging layer of composite powders, was perfect. The thickness of the packaging layer was between 50～100nm.
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