Aiming at the problems of difficult manual gangue picking, poor screening effect and unstable coal quality in the existing production system of Gulong Coal Industry, this paper carries out the research on the design of coal preparation process of supporting coal preparation plant. The coal quality characteristics and washability of No.15 coal were analyzed. Based on this, the washing process of raw coal with 8 mm powder removal, 80 ~ 8 mm grade raw coal with jigging machine separation, coarse slime centrifuge recovery, fine slime concentration and pressure filtration recovery was determined, and the corresponding process flow was formulated. The process can effectively discharge gangue, stabilize product quality, and improve coal utilization efficiency and economic benefits.