Abstract: The influences of column diameter and height on the countercurrent flotation process were discussed, and the new concepts of choked air bubbles and area load were put forward. By studying the force and movement of mineralized bubbles, a theoretical model expressing pulp movement was set up and model parameters were treated by experience. The column diameter was designed based on the pump velocity, and the column height was designed based on the column diameter and the column. Experiments were carried out to process molybdenum bismuth fine ores. The experimental results show that under the same test conditions, both the concentrate grade and the concentrate recovery of the flotation column whose size is designed based on this method are higher than those of other size flotation columns.