Abstract: To optimize the separation process of power coal in Ningdong mining region,especially to solve the problem of easy-to-sliming of non-caking coal in the process of all size separation. By analyzing the characteristics of power coal and production process of the existing coal preparation plant,proposed the reducing slime content in the process of production and process of coal slurry two stage thickening + purifying thickening,summed up overall processes,which suitable for power coal washing in Ningdong coal preparation plant,and presents a reference for construction of coal preparation in this mining area.