Abstract: In order to increase the yield of clean coal and optimize the product mix, the middlings product of the heavy medium separation system of Guotun Coal Washery is selected as the object of study for conducting an investigation into the feasibility of having such a product rewashed after it is being liberated through crushing. As evidenced by test result, through rewashing the middlings which is reduced in size from 50~0.5 mm to 3~0.5 mm, there can be seen an increase of yield and a rise of ash of high-density materials. This indicated that through the rewashing process, more recovery of up-to-standard clean coal and more removal of high-ash rejects can be expected. Moreover, the addition of the middlings crushing and rewashing system requires only limited capital cost yet a substantial profit can be generated per year. As viewed from such aspects as satisfactory test result, easy incorporation of the rewashing system and favorable economic result, the rewashing of the crushed heavy-medium separated middlings is highly feasible and operable.