Intensification of the density stability in the air dense medium gas solid fluidized bed is significantly important to the separation efficiency of this density-based separator. A binary dense media composed of the magnetite powder and quartz sand was used to achieve the intensification of the density stability. The fluctuation characteristics of the bed pressure gradients were investigated to seek for the optimum composition of binary dense media. The weight proportion of quartz sand in the binary dense media should not exceed 30%. The stability and uniformity of the bed density along the axial and radial directions of fluidized bed were experimentally investigated. The results indicated that the weight proportion of quartz sand should be controlled within 10%-20%, and the fluidization number should be adjusted from 1.5 to 1.6. A reliable mathematical model was established to predict the bed density. The calculation and measurement results agreed well, which validated the prediction accuracy. With a 10% weight proportion of quartz sand, the ash content of -13 + 6 mm sized coal was decreased from 33.35% to 11.55% with a clean coal yield of 69.48% at a fluidization number of 1.6. A satisfactory probable error value of 0.095 g/cm(3) indicated notable separation performance.