Abstract: The compound collector was proposed to improve the efficiency of separation with difficult-to-separate slime surface characteristics. New collector mainly composite hydrocarbon oil, fatty acid and surface active agent in order to enhance reagent adsorption ability. The data of IR spectrum and Zeta potential was used to explain adsorption mechanism of the medicament on difficult-to-separate slime surface. The adsorbed capacity of ZM collector was obviously higher than that of kerosene, but when the coal slurry density +1.7 g/cm³ the situation was opposite. The IR spectrum showed that the adsorption of ZM was obvious on organic components of coal particle surface, but it was no obvious on inorganic components and sulfur components. Thus the changes of zeta potential further validated that the ZM agent reinforced floatability of difficult-to-separate slime.