A two-dimensional numerical gas-solid flow models without chemical reactions were developed to simulate gas-solid flow in the Biomass fluidized bed boiler with a height of 300 cm and width of 57 cm through MFIX software. Two main different zones can be distinguished in terms of granular flow mechanisms. According to the distributions of instantaneous particle velocity and concentration at the boundary layer near the wall, there is a maximum velocity at about 60 cm in dense phase area which connects refractory with the water wall in height direction. In this area the particle phase concentration gradually accumulate and the direction of flow motion changes. Considered that the velocity and concertration are the main factor affecting wear and tear. These areas are considered as the most serious regional wear.