To study the fluidization characteristics and separation performance of a gas-solid dense-phase fluidized bed, bed space structure and force analyses of particles in the radial and axial zones are explored. The results indicate that the standard deviation and average bed density increases with increases in the static bed height. As the fluidization number is increased, the average bed density decreases and fluctuates drastically. Under the same fluidization number, the density in the upper layer is low with violent fluctuations, and it is relatively lower in middle layer and higher on the side wall. The ratio of the minimum pressure gradients in the axial and radial zones in the fluidized state was 10, which proved that the main movement mode of particles is settlement motion in the axial direction. The probable error values were 0.095 and 0.097 g/cm(3) in optimal test conditions, indicating efficient separation of 13-25 mm coal particles. (C) 2019 Elsevier B.V. All rights reserved.