Abstract: In order to improve processing capacity and clean coal yield of Changcun coal preparation plant,the raw coal size composition and washability were analyzed. The products structure,separation method and process were determined following the principle of reasonable matching of original and new system. The raw coal was high- medium ash,ultra- low sulfur coal type,the size fraction was evenly distributed and the gangue was hard. The low- density and high- density materials content in raw coal were high,the ash of above materials both were proportional to the density. The medium- density material was low. So the gravity separation was suitable for the raw coal. The products were high- ash clean coal and high- purity gangue. Based on the raw coal properties and products structure,two preparation processes were determined. One process was that- 50 mm raw coal was deslimed using jigging method first,then separated with TBS,at last flotation. The other process was that- 50 mm raw coal was deslimed using three- product dense medium cyclone,then separated with TBS,at last flotated. The transformation improved clean coal yield and circulating water quality,meanwhile make the jigging process run well.