With the increasing mechanization of coal mining, the proportion of fine coal being mined has been rising. To date, the problem of dry separation of fine coal has not been satisfactorily solved. Based on analysis of the surface structure characteristics of a compound dry separation machine, an experimental system with a compound dry separation unit for fine coal separation was established. We analyze the most important structural elements: the effect of the bed plate on fine coal separation and the distribution of the unit bed material layer of the ash separator unit under different structural partition conditions. The value of the comprehensive index, segregation degree of ash and separation efficiency were introduced for evaluation of results. The results indicate an optimum set of baffle parameters (theta = 45, d = 55-60 mm, and h = 60 mm) for which the segregation degree of ash in the bed material S-ash is 0.98, the maximum value of the comprehensive index P is 3.43, and the separation efficiency is the highest. (C) 2017 Elsevier B.V. All rights reserved.