Abstract: The problem facing the plant is that the yield of clean coal is limited because of the necessity to keep the ash of clean small coal to a level much lower than necessary. Following an analysis of the inherent causes and influential factors, an optimum scheme for tackling the problem is worked out. Practice shows through reducing fluctuation of ash of coarse clean coal, improving desliming efficiency of CSS and regulation of operation of flotation system, the quality and yield of clean coal is much enhanced.