Abstract: Circulating fluidized bed( CFB) power generation technology has been rapidly developed and widely used due to its unique advantages. In recent years,in order to achieve the goals of ultra-low emission and ultra-low energy consumption,the design and research of large-scale and high-parameter ultra-supercritical CFB boiler) has become the main development direction of clean coal power generation technology in China. At present,the basic theory and design calculations of ultra-supercritical generating units are not perfect,so it is particularly important for the simulation of its operation and the prediction of the main parameters of the boiler when the operating conditions change. Aspen Plus can perform sophisticated steady-state simulation and process design of complex chemical processes. Based on the built-in modules provided by the Aspen Plus software and the external subroutines of the FORTRAN compiler,the simulation model of coal decoupled combustion process in combustion chamber of a 660 MW ultra-supercritical CFB boiler was established. The process simulation model mainly includes the equivalent pyrolysis model of coal,simplified decoupled combustion model,separator,external bed and tail flue low temperature superheater and low temperature reheater model. Based on the established steady-state model,the performance of the 660 MW ultra-supercritical circulating fluidized bed boiler under full-load operating conditions( B-MCR) was simulated and calculated. The calculation results of its main temperature can be obtained,the gas component concentrations in the dense phase zone can be analyzed and the sparse phase zone in the combustion chamber,and the influence of the primary air ratio of the CFB combustion chamber operating parameters on the concentration of CO2,CO and SO2 in the dense phase zone and the influence of excess air coefficient on the concentration of the exhaust gas components SO2,SO3,NO and N2 O can be successfully predicted. At the same time,the model was used to calculate the effect of excess air coefficient and changing the ratio of primary return material on the outlet steam temperature of medium temperature superheater,low temperature superheater,and the temperature of flue gas at low temperature reheater and economizer. The design and research of the 660 MW ultra-supercritical circulating fluidized bed boiler provides a reference basis for reducing pollutant emissions,reducing boiler heat loss and improving boiler efficiency.