The present invention relates to an apparatus for absorbing and mineralizing carbon dioxide comprising a reactor and a three-phase separator, in which said reactor comprises a tower body and a draft tube disposed inside the tower body, a liquid inlet pipe and a gas intake pipe being disposed on the tower body, the outlet ends of the liquid inlet pipe and the gas intake pipe both being located inside the draft tube; and the three-phase separator is disposed at the upper end of the reactor, and a method therefor. The arrangement of draft tube inside the reactor of the present invention, enhances gas-liquid-solid mixing state because of the flow with airlift loop flow inside the reactor, accelerates the dissolution rate of solid alkali solute and thus may increase absorption reaction rate and absorptivity; the integration of three-phase separator in the reaction apparatus may isolate carbonate by settling while reacting, reduce solid content of the solution, while reducing the circulation of water between absorption and separation units, improve process performance, reduce process energy consumption; carbonate particles generated can be controlled better, thus a higher settling efficiency can be obtained.