Separation performance is the most important parameter for a continuous gas-solid separation fluidized bed. In this work, the separation process and its influencing factors in fluidized bed were studied by using a combination of stratified sampling method and sink-float tests. The results showed that the axial density distribution of coal particles was mainly determined by the density difference and fluidizing gas velocity (or bubble), while the lateral migration process was mainly affected by the moving scraper. The use of suitable operational parameters (u < 14.74 cm/s or u(f) < 6.0 cm/s) can reduce the bed resistance to density stratification of coal particles, thus improving the overall separation efficiency. Furthermore, under the optimumoperating parameters (u(f)= 4.4 cm/s, u= 13.26 cm/s), the lowest possible error E value of 0.06 g/cm(3) was achieved, indicating that the fluidized bed has high separation efficiency under these operating conditions. (C) 2020 Elsevier B.V. All rights reserved.