Abstract: The reaction of CaCl₂ solution with CO₂ in ternary amine was studied. In this multiphase reaction, calcium carbonate yield and amine extraction efficiency increased with the increase of CO₂ pressure and CaCl₂ concentration. The equilibrium of the reaction was analyzed by thermodynamics model coupled with Pitzer electrolytic solution model and a modified Henry’s law CO₂ solubility model. The distribution of hydrochloric acid in aqueous and amine is restricted by extraction equilibrium. The concentration of H⁺ could affect the dissociation of carbonic acid, which determines calcium carbonate precipitation/dissolution equilibrium. The activity coefficients of HCO₃^- and CO₃²- decreased with the increase of CaCl₂ concentration at constant CO₂ pressure condition, and influenced the equilibrium. The calcium carbonate yield and amine extraction efficiency were close to the calculated equilibrium values, and the reaction is controlled by chemical equilibrium.