Abstract: Limestone/gypsium or MgO is predominantly used by large chemical sectors for control of SO₂ emission in China. By incorporating the special merits of the above-mentioned two technologies, a novel dual-alkali desulfurization reagent prepared with MgO, CaO and some basic solid waste is developed. The effect of temperature on solubility of MgO and the novel desulfurization agent, and the effect of initial concentration of sulfides on pH value of aqueous solutions of MgO and the novel agent are explored through comparison and analysis. Result of study indicates that at normal temperature, the lower the initial concentration of sulfides in sulfurous wastewater, the faster the reaction rate of MgO and desulfurization agent with sulfides, and their reaction can be completed within 3 minutes. The novel agent proves to be a high-efficiency flue gas desulfurization reagent.