Abstract: In the production process of smelting and thermal power enterprises, the main heat energy is supplied by coal, but because of the combustion of coal, a large amount of sulfur-containing flue gas will be produced, and the existence of sulfur-containing flue gas will seriously affect health and pollute the ecological environment. Therefore, driven by environmental protection requirements and the concept of green development, flue gas desulfurization must be carried out, and flue gas desulfurization has become a necessary way for smelting and thermal power enterprises to maintain clean production. At present, according to the types of desulfurizers and the state of desulfurization products, flue gas desulfurization (FGD) technology can be divided into three categories: wet, dry and semi-dry. Each of the three flue gas desulphurization methods has its advantages and disadvantages. Three typical processes are selected and their desulfurization processes and principles are introduced, aiming at giving readers a more comprehensive understanding of flue gas desulfurization technology and providing technical reference for solving the problem of flue gas desulfurization.