Abstract: Circulating fluidized bed( CFB) boiler has the advantages of wide adaptability of coal type,strong load regulation ability,ultralow emission of pollutants,etc,which is widely used in clean combustion of coal. In order to explore the generation and emission of pollutants in CFB,a systematical modelling and prediction of a 0. 3 MWthCFB coal-fired pilot facility based on the Aspen Plus scheme were conducted,including the sub-models of coal combustion and pollutant control devices. The Gibbs minimum free energy thermodynamic analysis method was used to analyze and calculate the coal combustion products,and the sensitivity analysis tool included in the software was used to analyze the sensitivity of different operating parameters. The effects of operational parameters of the combustion system on flue gas components,denitrition of selective catalytic reduction( SCR) and desulfurization of limestone-gypsum wet flue gas were predicted. The variable process of NOx,SOxremoval efficiency and generation of SO3 versus the excess air coefficient,flue gas temperature,ammonium to nitrogen ratio and calcium to sulfure ratio was simulated. The results show that under the conditions of circulating fluidized bed coal combustion,the changes of temperature have a significant effect on the formation of NOxand SOx. The increase of temperature will promote the conversion of NH3,HCN and other precursors,and promote the production of fuel nitrogen to NOx; under high temperature conditions,the chemical equilibrium of the SO2 formation reaction moves to the positive direction,but the reaction rate decreases with the increasing of temperature and concentration,while SO3 is the opposite. During the SCR denitration process,the denitration rate increases with the increase of temperature at lower temperatures,and the optimal active temperature is around 360 ℃ . Before the reaction temperature of SCR is 380 ℃,the content of SO3 increases significantly,and there is a maximum value point at 380 ℃,and then tends to be gentle and slightly decreases. When the ammonia-nitrogen ratio is less than 1,the denitration rate promotes with the increase of the ratio of ammonia to nitrogen,and the best ratio is 1.05. During the WFGD desulfurization process,increasing of the calcium-sulfur ratio can significantly enhance desulfurization efficiency and reduce the emission of SO3,and the best ratio of calcium to sulfur is about 1.05. The elevation of WFGD inlet temperature results in less desulfurization efficiency but promotes the formation of SO3.