Lime: theoretical concepts of active lime, is a chemical properties and lively, strong ability to participate in the reaction, containing S (sulfur), low P (phosphorus) and other harmful impurities. It has the following main characteristics: volume density, porosity, large surface area, the reaction performance. At the same time, Shanxi lime, it has: CaO crystal fine: ≤1 wm, processed lime, CaO content: ≥90%, low lime powder, S, P content: <0.02% and traces, SiO2 + Fe2O3 + Al2O3 content is low: < 2%, low residual CO2: ≤2% lighter and other characteristics of burnt lime. The main reaction limestone wet desulphurization processes: wet limestone desulfurization process is typical of gas chemical absorption process, the occurrence of complex chemical reactions in flue gas cleaning process. Removal of SO2 from flue gas process is carried out in the gas, liquid and solid, the occurrence of gas - liquid reaction and liquid - solid reaction.