Desulfurizing agent and preparation method thereof

The invention particularly relates to a desulfurizing agent and a preparation method thereof, and belongs to the technical field of flue gas desulfurization, and the method comprises the following steps: carrying out solid-liquid separation on red mud underflow to obtain red mud liquid and wet red mud; mixing a poising agent, a modifying agent and the red mud liquid to obtain a red mud digestion liquid; mixing and grinding calcium oxide, a high-aluminum material and desulfurized fly ash to obtain a digestion precursor; reacting the red mud digestion liquid with the digestion precursor to obtain a first-stage digestion product; mixing the wet red mud, the first-stage digest and a composite metal oxide to obtain a first mixture; mixing the first mixture with a solvent, and then performing evaporation drying to obtain a second mixture; roasting the second mixture to obtain a second-stage digest; grinding the second-stage digesting material to obtain a desulfurizing agent; a calcium oxide digestion reaction is en