This paper describes the influence of molecular structures of polymer on the fluidity of CaCO₃ suspension with inorganic salts. With the addition of K₂CO₃, the fluidity of suspensions dosed with comb-type superplasticizers is significantly decreased, which appears to correspond to a decrease in the amount of polymer adsorption. This reason was due to the decrease of Ca²⁺ sites on the surface of particles, leading to the reduction of adsorption sites of the polymer. The polymer having shorter graft lengths is adsorbed more easily even though the number of adsorption sites is decreased, since the shorter the length of the graft chain, the larger the content of carboxyl groups on the main chain of comb-type polymer. The intervals between graft chains were prolonged, with changing composition of the copolymer where methoxypolyethylene is replaced by styrene or allyl sulfonates. When a larger amount of carboxyl groups were introduced on the main chain or when the distance between graft chains was extended, the influence of the inorganic electrolytes on the fluidity of suspension with polymer was decreased. In addition, the introduction of sulfonate groups increases the affinity between the polymer and the solid. These polymers can be adsorbed on CaCO₃ even though the adsorption sites are decreased upon adding inorganic salts. This may decrease the influence of the inorganic electrolyte on the fluidity of CaCO₃ suspension.