Abstract: The mechanism of a new air flotation equipment with an air-water mixing chamber is explained. The removal efficiency of the equipment is determined under experimental conditions. For substances such as petroleum and suspended solids(SS), the removal efficiency is more than 95%. The experimental data are analyzed, and the relationship between the removal efficiency of the equipment and the rotational velocity is discussed. It is found that the removal efficiency increases with the rotational velocity before arriving at an optimal rotational velocity, and decreases over the optimal rotational velocity. Meanwhile, an empirical formula for evaluating the optimal rotational velocity is obtained.