In recent years,the development of dry separation technology of air dense medium fluidized bed(ADMFB）provides an effective way for clean coal processing in arid and water deficient areas of the world. In the dry heavy medium fluidized bed,the updraft drives the fluidization of dense medium to form a gas-solid two-phase flow bed with pseudo-fluid properties,which creates a uniform and stable fluidization environment suitable for coal separation. The coal particles migrate,float and sink in the bed,and are separated according to density under the comprehensive action of gravity,air drag,medium resistance,bed buoyancy and other forces. The characteristics of coal particles,bed density distribution and operation parameters of fluidized bed are the critical factors affecting the suffering force,settlement characteristics and separation effect of coal particles. Therefore,the migration process of dense particles in the fluidization process and the spatial distribution of bed density were studied. The uniformity and stability of bed density were quantitatively evaluated. The influence of particle size,density,immersion depth and gas velocity on the force properties of coal particles was studied. The response surface method was used to compare the disturbance law and influence degree of different factors. The correlation between the influencing factors and the comprehensive force of coal particles was established. The migration path and stable distribution area of each density component of coal particles with different densities were determined. The results show that the ADMFB with uniform density can be formed by using magnetite powder(0.300-0.074 mm,2.36 g/cm³）and glass powder(0.300-0.074 mm,1.14 g/cm³）as the binary medium. The binary dense particles are mixed evenly and stably. The bed density fluctuation can be controlled within ±0.01 g/cm³. The significant degree of the main influencing factors on the force of the selected particles is in the order of particle size,immersion depth and gas velocity. After coal particles are fed into the bed,the density components are rapidly loosened,settled and stratified. The separation time is less than or equal to 8 s. The coal particles with density higher than bed sank rapidly and settled in the area below the bed height of 40 mm. The coal particles with density lower than the bed are loose and migrate laterally along the area near the bed surface,and are distributed in the area above 160 mm. The middle density particles are loose and settled,which are distributed in the bed area above 45 mm.