The properties of CO₂-modified recycled aggregates with different qualities and particle sizes have not been investigated systematically and comprehensively. In the conditions of 20% CO₂ concentration and natural environmental pressure, considering the effect of recycled coarse aggregate (RCA) quality and particle size, the carbonization rate, CO₂ absorption, alkalinity, water absorption of CO₂-modified recycled coarse aggregate (CRCA) and residual CO₂ content in CRCA were investigated; the compressive strength and chloride penetration resistance of CO₂-modified recycled coarse aggregate concrete (CRAC) were also evaluated. The results show that the carbonization rate and CO₂ absorption of CRCA increase with the increase of CRCA water-cement ratio; the CO₂ modification significantly reduces the alkalinity of RCA; the smaller particle size and lower water-cement ratio of CRCA, the more CO₂ sequestrates in CRCA; the CO₂ modification remarkably reduces the water absorption of CRCA and significantly improves the compressive strengths and chloride penetration resistance of CRAC.