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Low calcium β-C2S and γ-C2S minerals with low hydration activity was activated by accelerated carbonation curing to be used as new binding materials. Synthetic β-C2S and γ-C2S were synthetized and compacted to prepare cube samples and then subjected to CO2 chamber for accelerated carbonation curing. The CO2 uptake, mechanical strength, and microstructure changes of β-C2S and γ-C2S were analyzed by TG, XRD, MAS-NMR, and MIP. The experimental results indicate the CO2 uptake of γ-C2S is much higher than that of β-C2S, but the compressive strength of γ-C2S samples is lower than that of β-C2S. Calcium carbonate and other carbonation products stack in the pore structure and the porosity is reduced from about 42％ to 30.1％ and 22.0％ for β-C2S and γ-C2S samples after 2 h carbonation curing, respectively. The difference in compressive strength development is caused by the different properties of carbonation products. Except for calcium carbonate, there also exists obvious difference in properties of amorphous phases: γ-C2S formed silica gel in the whole carbonation progress; however, β-C2S can react to produce silica gel and C-S-H gel with high Van der Waals forces, and C-S-H gel will continue to react with CO2 to form calcium carbonate and silica gel in later carbonation reaction; In addition the microhardness of carbonated β-C2S was more higher than that of γ-C2S.