Abstract: Three-dimensional flow field in a 50 MW biomass circulating fluidized bed (CFB) boiler was simulated using Eulerian model, so as to study the gas-solid two-phase flow and to analyze the wear condition in the boiler. Results show that the simulated distribution of bed pressure agrees well with that of actual measurement. On both the front and back wall of CFB boiler, the solid phase is sparsely distributed in the upper part but densely distributed in the lower part, in the “S” shape. The most serious wear appears at the position of y=0.95 m, and the wear on front wall is more serious than on back wall.