Abstract: In order to better guide the industrial production,understand the state of particles of different particle sizes in the gas-solid fluidized bed and the distribution of particles in the fluidized bed,the fluidization characteristics of the narrow-screened particles in the gassolid fluidized bed were numerically simulated.The flow field simulation software was used to analyze the volume fraction and the height of the fluidized bed and the time required to reach this target under the conditions of particles with different particle sizes( 46-80,106-113,185-221 μm) in the same fluidized bed and different inlet velocity of the fluidized bed. The Euler-Euler model and SIMPLE algorithm were used to calculate the particle volume fraction and velocity distribution under different gas velocity conditions.The results show that the increase in particle size causes the larger difference between the highest point and the lowest point of the particle volume fraction in the fluidized bed under the same gas velocity,meanwhile,the unevenness of particle distribution increases,the overall height of the bed decreases,the particles in the bed density increases,the fluidization decreases with the decrease of the volume fraction of the particles.In the case of the same particle size,increasing the gas velocity can reduce the volume fraction of particles inside the fluidized bed,increase the contact area of the gas and solid particles,and enhance the fluidization effect.However,the time of the particle velocity vector distribution inside the fluidized bed reaching a uniform is reduced,and the uneven distribution of particles is more obvious.