Abstract: The characteristics of different Ca-based CO₂ absorbents in the process of cyclic calcination-carbonation were investigated. The variation of microstructure, pore radius and specific surface area of the absorbent with different crystal lattice configurations during the cycles was researched, and the main reason that affects the reactivity of the absorbent was analyzed. The results show that the stability of CO₂ capture capacity of the calcined dolomite is higher than that of the calcined limestone. Dolomite includes MgO that can change the atomic framework of the absorbent, in turn reduce the plugging of the pore due to the formation of CaCO₃ and keep the reactivity of absorbent.