Abstract: What was originally used in the plant's raw coal treatment workshop was a labour-intensive hand-picking system which restricted the hoisting operation of the mine and caused a high failure rate of equipment. The paper first presents an analysis of the problems encountered in the coal washing system from the equipment selection aspect,and then elaborates on the necessity of making technical transformation of the shallow-trough dense medium separation system for deshaling purpose. Based on result of analysis and in consideration of the raw coal property and specific requirement,a series of remoulding measures is taken. Practice shows the remoulding work has produced remarkable result-noticeable increase of yield of clean coal,decrease of content of dirt in raw coal feed,less wear of H. M. cyclone,feed pump,screenplate and reject transport belt,increased coal washing efficiency and raw coal preliminary treatment capacity,elimination of adverse effect on mining operation and cut-down of consumption materials and spare parts and save of maintenance cost.