Abstract: The effects of SO₂ on the cyclic calcination and carbonation characteristics and the cycling stability of calcium-based CaCO₃ sorbent for CO₂ capture were investigated in a cycling calcination/carbonation system. The results indicated that the capacity of CaCO₃ sorbent for CO₂ capture decreases with the increase of the number of calcination/carbonation cycling and the addition of SO₂ will further reduce the capacity for CO₂ capture; moreover, the decrease of the capacity for CO₂ capture may be aggravated at higher SO₂ concentration. After 10th cycling, the carbonation conversions of the sorbent under SO₂ concentration of 0, 0.1% and 0.2% are 25.5%, 16.9% and 5.2%, respectively. SEM characterization results revealed that sulfate products are formed on the surface of CaCO₃ particles in the presence of SO₂; the sulfate products block the sorbent holes and then reduce the diffusion rate of CO₂ into the sorbent, which may then reduce the capacity of the calcium-based sorbent for CO₂ capture.