Coal gas-solid fluidized dry separation is an important and effective way for fine-grained coal separation to improve quality,mineral processing and solid waste recycling in arid and water-scarce regions and alpine regions,and it has great industrial application potential. At present,the fluidized bed used for separation has been studied by many researchers. The basic theory has been studied in depth,including the formation of fluidized bed,fluidized bed aerodynamics,fluidized bed flow model and simulation,etc. However,the low-density separation technology and density adjustment range of dry dense medium fluidized bed still need to be improved. The reasonable selection of dense medium is of great significance to the coal preparation of dry dense medium fluidized bed. It is closely related to the purification and recovery process of the fluidized bed dry coal preparation system,the operation parameters of the separator and the separation effect. A self-made fluidized bed was used to study the fluidization of single component,narrow particle size and wide particle size in two-element dense medium,and the fluidization characteristics of three-element dense medium in a fluidized bed were studied. The fluidization characteristics,expansion rate and particle size of magnetite powder and paigeite powder were compared and analyzed. The results show that both magnetite powder and paigeite powder can reach good fluidized state. With the decrease of dense medium size,the initial fluidized gas velocity decreases significantly,and the expansion property increases gradually. Compared with the mixture of 150-125 μm paigeite powder and 74-45 μm magnetite powder,the bed pressure drop fluctuates more with the mixture of 125-74 μm paigeite powder and 74-45 μm magnetite powder. Under nine different weight ratio conditions,the bed pressure drop of 300-74 μm paigeite powder and 74-45 μm magnetite powder has no obvious fluctuation. With the decrease of the size of dense medium,the expansion property gradually increases. The homogeneity degree of the two-element narrow particle dense medium increases with the increase of the content of paigeite powder. When the two-element wide particle size dense medium is mixed,the approximate horizontal section of the fluidization curve fluctuates more with the increase of fine particles,which is not conducive to form a stable separation environment. With the increase of pulverized coal content,the fluidization effect of ternary dense medium gradually becomes worse. In order to ensure good uniform stability of fluidized bed density,the content of pulverized coal in ternary dense medium should not exceed 15%.