Abstract: During the increasingly serious environmental problems and the ultra-low emission implementation of coal-fired boiler,the air pollution problems caused by coal combustion and the combined effect of the flue gas desulfurization( FGD) and dust removal equipment to remove pollutants gradually has been drown great attention. The SO_2 and particulate matter released from coal combustion cause serious harm to human health and the natural environment,and it is of vital importance to control the SO_2 and particulate matter.In this paper,the development history,technical characteristics and scope of application of the wet FGD technology such as Limestone-gypsum method,ammonia method and so on,semi-dry FGD technology such as circulating fluidized bed flue gas desulfurization technology,No Gap Desulphurization technology and so on,and dry FGD technology such as Electron ray radiation desulfurization technology,activated carbon( active coke,active semi coke) adsorption desulfurization technology and so on were reviewed.The effect of the FGD system on the emission characteristics of particle was analyzed.the results show that the wet flue gas desulfurization technology has the highest SO_2 removal efficiency,especially the limestone-gypsum flue gas desulfurization technology,and the total efficiency is more than 99%.When the inlet particulate matter concentration is higher than 5 mg/m3,the technology can synergistically remove particulate matter in the flue gas,and the dust removal efficiency can reach 50%-80%.The particle size distribution before and after desulfurization is a typical bimodal distribution,and the peak value of particle size shifts to a small particle size after desulfurization,and the sulfate content increases.When the mass concentration of particulate matter at the inlet is less than 5 mg/m3,the particle concentration at the outlet may increase instead of decreasing.However,due to the disadvantages of high investment and operating cost,it is mostly used in large coal-fired units and areas with rich sources of desulfurizer,and the products of wet flue gas desulfurization also have certain economic benefits.The desulfurization efficiency of the semi-dry and dry FGD is about 60%-90%.Compared with FGD,the semi-dry and dry FGD may have a good prospect in the field of small and medium boilers such as coal-fired industrial boilers due to its low investment and operating costs,small size and water conservation.Thus,a large amount of desulfurization products and desulfurizers enter into the dedusting equipment along with the flue gas,the particle concentration at the inlet of dust removal equipment is higher than 1 000 g/m3,which causes great operating pressure for the dedusting equipment and increases the investment and operating cost.At present,there are few studies on the effects of semi-dry flue gas desulfurization technology and dry flue gas desulfurization technology on the emission characteristics of particulate matter. It is necessary to further study the influence of the desulfurization system on the particle size,composition,and morphology of particulate matter.