Abstract: A dynamic modeling method for large scale circulating fluidized bed boiler is presented in this paper.Cell approach is used to simulate the axial distributions of solid and gas phase in the bed,and ’core-annular’ construction is used to describe the radial distributions of solid particles and particle cluster.Meanwhile,it takes into account the influence of wide size distribution of both bed and feed materials on hydrodynamics,chemical reactions and heat transfer.Integration of CFB loop,steam-water and air/gas system model for circulationg fluidized bed boiler and a partitioning and multi-rate integration technique for solving the integrated model is as also presented in the paper.Based on the method,simulations of static and dynamic performance for 410t·h ^-1 Pyroflow CFB boiler is carried out.The results show that the model is capable of predicting the overall performance of CFB boiler.The modeling method has theoretical and engineering significance for the research of combustion technology,large scale boiler design and operating performances of circulating fluidized bed boiler.