A modeling method for a large-scale circulating fluidized bed (CFB) boiler is presented. The method uses the cell approach to simulate the axial distribution of solid and gas phases in the bed and uses 'core-annular' construction to describe the radial distributions of solid particles and particle clusters. At the same time, it takes into account the influence of the wide size distribution of both bed and feed materials on hydrodynamics, chemical reactions and heat transfer. The steam side dynamic characteristics of the boiler are also considered based on the modular modeling method. Based on the method, simulations of static and dynamic performances of a 410 t/h Pyroflow CFB boiler are carried out. The results show that the model is capable of predicting the complete performance of the CFB boiler. The modeling method has important theoretical and engineering values for the research of combustion technology, large-scale design and operating performances of a circulating fluidized bed. (c) 2006 Elsevier Ltd. All rights reserved.