Abstract: To improve the efficiency of treating high concentration slime water with flotation column,the pre-flotation column was designed which using a new way of feeding method,and then studied the separation efficiency of this new flotation column separating slime water under different pressures and concentrations.Based on comparing the separation efficiency between the new flotation column and traditional flotation column,the results showed that when the feeding at high concentrations condition,and the ash content of clean coal of pre-flotation column closing to or slightly lower than traditional flotation column,the clean coal yield generally higher 1%-4% than that of conventional flotation column,and improved floatation index by 1.2%-4% than traditional flotation column.All of this proved that the separation efficiency of the pre-flotation column is better than traditional flotation column.