Abstract: Sulfur dioxide is one of the main pollutants that come from the tail gas of industrial furnace in alkali sulfide industry. The production process of sulfur dioxide was analyzed theoretically，and the basic principle of wet magnesia flue gas desulphurization（FGD） was introduced briefly.The relationships between desulfurization efficiency and several factors were studied，including the slurry preparation，absorption，oxidation，crystallization，and drying etc..It pointed out that this method can avoid the problems，such as absorption tower block and scaling.It had many characteristics，such as less investment and simple tower structure.The feasibility was also discussed from the economic angles，such as raw material supply and operation cost.Thus the flue gas desulphurization cost can be reduced and the profit space of by-product magnesium sulfate can be increased.The process can not only protect the environment，but also create a good economic benefit for the enterprise.Only in this way，the enterprises can realize sustained and healthy development and enhance the competitiveness.

Key words: sodium sulfide, magnesium oxide, flue gas desulfurization, sulfur dioxide, magnesium sulfate