Mortars were prepared using solid waste—circulating fluidized bed fly ash and flue gas desulphurisation gypsum as mineral admixtures. The carbon sequestration capacity， mechanical properties and reaction mechanism of mortars under carbonation conditions were investigated through carbonation tests， strength tests， X-ray diffraction and scanning electron microscopy-energy spectroscopy. The results show that the incorporation of solid waste increases the pore space and the content of calcium source， and significantly improves the CO₂ absorption of the mortars. Furthermore， the mechanical properties of the mortars are significantly improved after carbonation and maintenance， and the expansion problem caused by high sulphur is eliminated. The application of this process can increase the utilisation rate of industrial solid waste in Inner Mongolia region by up to 36.5%.