A rate equation of small particle-air bubble attachment in the turbulent now of flotation cells has been derived. The equation, integrating both the collision probability and adhesion probability together, represents the probability of attachment between particle and bubble in the turbulent flow. “Capture efficiency” f(α) is introduced into the rate equation to reflect the influence of energy hairier on the attachment rate. Three typical situations of particle-bubble interaction in flotation process have been discussed. For a completely hydrophobic particle-bubble system,f(α) = 1. This means that all collision leads to attachment. Whereas for hydrophilic particle-bubble systems,.f(α) = 0. Thus no adhesion of particle on bubble occurs at all. In real notation circumstances, however, there always exists a certain energy barrier between the particle and the bubble. Therefore, f(α) = 0~1. In such cases, not all collisions result in particle-bubble attachment.