Abstract: Desulfurization of coal using gravity separation process offers the special merits of being low in environmental pollution, and simple in layout of process equipment.However, the bottleneck of this technology lies in its relatively low efficiency and limited sulfur and ash removal capacity.In order to im- prove the sulfur removal efficiency of the gravity separation process, the middle-sulfur Zichang coal is taken as the object of study.Following an analysis of the size and density characteristics of the coal the tabling and centrifugal separation test are both made to explore the sulfur removal and ash reduction effect that can be obtained by the combined process working in gravity-centrifugal force coupled field, as well as the operating parameters of each process and the effect of separation process on sulfur removal and ash re- duction of coal.Test result shows that for the reduction of ash of coarser particles, a better result can be obtained with the use of the tabling process while for the desulfurization of finer sizes, a better effect can be expected by using centrifugal separation process; as evidenced by result of the tabling-centrifugation combined separation test, a clean coal product with a yield of 30.36%, an ash of 19.33% and a sulfur content of 1.63% can be obtained-a significantly improved sulfur removal efficiency as compared with the use of a single process􀆰