Abstract: In order to solve the problem of flotation of coal slime,the influence of pH and metal cations on the coal flotation and flotation kinetics of coal slime was investigated. Results showes that the kinetics of coal flotation at pH 5.5 and 7.2 were higher than the other pH in all flotation process, whilst the ash flotation kinetics was lower than the other pH; According to the analysis of flotation kinetics,the effect of adding different metal cation on ash recovery is higher than that of coal, and the flotation rate is also increasing. In addition pH can effectively improve the coal recovery, whilst adding metal cation can leading the decreased of coal recovery.