As the most commonly used slime sorting equipment, heavy-medium cyclone is more efficient than hydraulic sorting equipment and flotation in the treatment of fine coal. In order to improve the separation effect of heavy-medium cyclone and the method of fine-grained slime separation, the influence of the properties of heavy-medium suspension as a separation medium on the effect of slime separation was studied. By changing density feed pressure, the differences in the stability of heavy media suspensions were explored, thereby affecting the fine coal sorting effect. The results showed that with the increase of coal slime content and suspension density, the concentration of heavy media suspension and stability increased, the clarity decreased. With the increase of feed pressure, the concentration of suspension increased and the stability decreased.