Abstract: The object of the study is a double-cone heavy-medium cyclone which has an upper and a lower conical parts. It is intended to analyze, through computional fluid mechanics numerical simulation, the pattern of velocity distribution of the fluid in the cyclone at different cone-angle combinations, so as to determine their optimum combination for separation of high-density oil shale. Result of study shows that: the internal flow field of the cyclone exhibits a similar distribution pattern at different cone-angle combinations; with a cone angle of 70°of the upper conical part and a cone angle of 30°of the lower conical part, the tangential velocity of the fluid tends to reach its peak value; and when the position of the zero-velocity envelop comes nearest the wall of the cyclone, a highest actual separating density can be expected. Hence, the cone-angle combination of 70°and 30°is finally selected.