Based on the technical reform engineering of Wanli No. 1 coal preparation plant, according to?the coal quality characteristics of high external moisture and high content of fine coal, replace the former vibrating screen with a relaxation screen, reform the heavy-medium shallow-trough separation process so that it can be connected in series or parallel, add a centrifugal dehydration process block clean coal after crushing, the moisture content of the product is reduced, the calorific value of the commercial coal is increased, and the clean coal yield is increased by 28% compared with that before the technical transformation. The total moisture of clean coal decreased by about 3.1% and the calorific value increased by about 148kcal/kg ,business turn loss into gain.Reference experience for the design of technical transformation project of large-scale steam coal preparation plant is provided.