Abstract: Pb released from coal-fired power plants is characterized by long-distance migration,bioaccumulation and persistent hazards.Although the content of Pb in coal is quite low,the amount of released Pb from the coal-fired power plant could cause serious environmental pollution due to the tremendous coal consumption.Due to the complexity of on-site sampling,the studies on the migration and emission characteristics of Pb in coal-fired power plants are very scarce. In this study,a 410 t/h circulating fluidized bed( CFB) boiler burning mixed fuel of coal and petroleum was selected as the research object,and the EPA Method 29 was used to simultaneously sample flue gas before and after fabric filter( FF) and wet flue gas desulfurization( WFGD).Meanwhile,the flue gas sampling,feed fuel,limestone,bottom ash,fly ash,gypsum,effluent water,limestone slurry and flush water were also sampled and analyzed.The distribution of Pb in combustion byproducts and the migration and emission characteristic of Pb were obtained based on Pb balance calculation. The results show that the mass balance ratio of Pb is in the range of 105.1%-106.4%,which indicates the high accuracy and reliability of the test.During the combustion process,the Pb released into the gas phase is mainly in the gaseous forms,such as Pb~0 and PbO,only a small part remains in the bottom ash.In this study,Pb in bottom ash accounts for 13.7% of the total Pb in the whole system.With the flue gas flow and temperature decrease,most of the Pb compounds in the flue gas will undergo the processes of homogeneous nucleation,heterogeneous condensation,deposition and adsorption on the particle surface to form particulate Pb.Therefore,at the outlet of air-preheater,particulate-bound Pb is the dominant species in the flue gas,accounting for over 99%; while the content of Pb released into the atmosphere is only 0.4%.The removal efficiency of Pb in the flue gas by the fabric filter is as high as 99%,which is mainly reflected in the removal of particulate Pb.The wet desulfurization tower has a certain removal effect on the water-soluble gaseous Pb and particulate Pb,and the removal efficiency can reach to 67%.After the removal by these pollutant control devices,the final concentration of Pb emitted into the atmosphere is extremely low( about 2.99 μg/m~3); and the emission factor of Pb is 0.90×10~(-12) g/J.