Abstract: One of the challenges in the flotation is the top size of the particles. Application of three phase fluidized bed technology,introduction of air bubbles rising water flow,and comparison with and without air bubbles on the influence of coal particle bed expansion degree were used to conclude that the introduction of bubble flow can strengthen the flu- idization of low density particles. And,under three kinds of flow conditions including rising flow in rising water flow on- ly,rising bubble flow and water flow,and bubble flow+collector (kerosene),a coal separation experiment was carried out. Results show that the introduction of bubble flow can significantly reduce the rising flow required for the level of low density particles suspended velocity,the bubble flow’s influence on the level of low density particles is better than that on high density coal particles,the existence of the bubble strengthens the coal density,and weakens the effect of particle size on separation. Adding collection agent in the rising bubble flow,the low density particles and bubble form a particle-bubbles combination,low density particles can be separated in a low rise water speed,in a low speed upward water,its steady flow degree is low which can guarantee the stability of the large particles and bubbles. With the addi- tion of the collection agent,the speed of the water flow will be closer for each grain grade particle separation,and the ash of each grain grade will be about 10% .