Abstract: In order to study the collision efficiency?between the bubbles in the pulp and the fine slime and its influencing factors in the process of flotation ,a numerical calculation method based on numerical simulation software FLUENT is presented ,then this method is used to simulate the bubble and particle collision behavior of different particle size, particle density, bubble diameter and turbulence intensity,the collision efficiency between bubbles and particles was calculated, and the effects of various factors on the collision efficiency of single bubble and coal particles were obtained.The results are as follows: particle size and bubble size are the main factors that affect the collision efficiency between bubble particles.With the increase of particle size, density and turbulence intensity, the collision efficiency increases.In the still water, the collision efficiency increases with the increase of bubble size;in turbulent flow, the collision efficiency decreases with the increase of bubble size.