The comb copolymer poly(acrylic acid) (PAA) grafted methoxyl poly(ethylene oxide) (MPEO) (PAA-g-MPEO) as dispersant was used in aqueous CaCO₃ suspensions. The PAA-g-MPEO was adsorbed onto CaCO₃particle surfaces due to the electrostatic attraction. The adsorbed amount increased with increasing PAA-g-MPEO content. The CaCO₃ adsorbed PAA-g-MPEO displayed negative zeta potential. The zeta potential was more negative with increasing PAA-g-MPEO content. Addition of PAA-g-MPEO, the conductivity of aqueous CaCO₃ suspensions decreased firstly, and then increased with increasing PAA-g-MPEO content. Compared to that of aqueous CaCO₃ suspensions, the viscosity of aqueous CaCO₃/PAA-g-MPEO suspension reduced remarkably, and the liquidity of the suspensions was improved. The dispersion of CaCO₃ particles in aqueous CaCO₃/PAA-g-MPEO suspensions was significantly improved due to electrostatic repulsions and steric hindrance between CaCO₃ particles adsorbed PAA-g-MPEO.