In order to achieve the national strategic goals of “peak carbon dioxide emission and carbon neutrality” in the building materials industry, a type of low-calcium carbon sequestration cementitious materials (LC-CSCM) was prepared by calcining industrial calcareous and siliceous raw materials at 1 350 ℃. The influences of different concentrations of CO2 on the carbonation degree and the carbonation hardening performance of LC-CSCM were investigated. XRD, FT-IR, TG, SEM and EPMA were used for the evolution of product analysis, microanalysis and mechanism analysis of carbonated LC-CSCM. The results show that with the increase of CO2 concentration, the carbonation degree and the carbonation hardening performance of LC-CSCM increase significantly. When the CO2 concentration is 99.99% (volume fraction), the compressive strength reaches 132.2 MPa after 8 h of LC-CSCM carbonation curing; compared with the concentration CO2 of 25%, the compressive strength increases by 260%.