For the purpose of the gradual decrease of calcium carbonate resources and reduction of carbon emissions in wet flue gas desulfurization process, the utilization process of carbide slag to replace limestone is systematically analyzed. The properties of carbide slag and limestone have been analyzed, and the mass transfer and reaction behaviors in desulfurization process have been calculated and comprehensively evaluated. Desulfurization performances have been also compared through response surface analysis method. The results show that the calcium content and specific surface area of carbide slag are higher than limestone, which is conducive to the dissolution and mass transfer rate. Therefore, carbide slag is suitable for the treatment of flue gas with high SO2 concentration. Desulfurization efficiencies of the two desulfurization agents of carbide slag and limestone under the optimal process are 99.15% and 96.53%, respectively. In conclusion, carbide slag can be used in desulfurization process to replace limestone. The consumption of carbide slag slurry in the desulfurization process is about half of limestone slurry at the same conditions, and the higher desulfurization efficiency of carbide slag is attributed to the higher mass transfer and dissolution rate. Utilization of carbide slag also reduces the carbon emission in desulfurization process and economic cost. The reduction amount of CO2 emission can reach to about 0.76 t /t carbide slag. This work provides a basis for the industrial application and desulfurization efficiency improvement of carbide slag as the desulfurizer. (c) 2022 Published by Elsevier Ltd on behalf of Institution of Chemical Engineers.