It is environmentally friendly to crush waste concrete as recycled aggregate for cyclic utilization, and it also can solve the shortage of natural aggregate. However, the performance of the recycled aggregate concrete was poor caused by the surface adhesion of old cement mortar on the aggregate and the micro crack properly generated during the crushing process. The pressure pretreatment on recycled coarse aggregate by CO₂ was used to improve its basic performances. The variables carbonization time (0h, 6h, 12h, 24h, 48h, 72h) and CO₂ carbide gas pressure (0.1MPa, 0.4MPa, 0.8MPa) were studied, and the basic properties of recycled coarse aggregate before and after carbonization were compared and analysed, and the degree of improvement on recycled aggregate concrete were also investigated to determine the optimal scheme for carbonation, which was in the container with 0.4MPa pressure for 24h. Based on the optimum carbonation scheme, the influence of recycled coarse aggregate on mechanical properties of recycled aggregate concrete was studied with the substitution rate of recycled coarse aggregate (30%, 50%, 70% and 100%) before and after carbonization respectively. The results showed that the CO₂ reinforced recycled coarse aggregate water absorption rate and crushing index was decreased, apparent density was increased. At the same substitution rate, the compressive strength and elastic modulus of carbonized recycled aggregate concrete was higher than that of non-carbonized recycled aggregate concrete.