Abstract: In order to explore the pattern of distribution of materials on trough surface of spiral separator, test is made on separation of the coarse-grained coal slime with 9 different size compositions from Daliuta Coal Preparation using the 5LL-Φ600 spiral separator. Then the separated products respectively obtained are analyzed. As evidenced by test result, the ＞0.125 mm material can be effectively separated with the separator; when the material size is smaller than 0.125 mm, it is disadvangeous to its separation due to no distinctive material stratification and zoning effect on trough surface; the material tends to undergo stratification in the radial direction on trough surface with lighter particles in upper layer and heavier particles in lower layer; the material tends to become zonated in the longitudinal direction with the heavier particles on the inside and the lighter particles on the outside; and the separation process is effected according to both density and size. It is noted therefore the size range of the material can exert a great influence on result of material separation; the wider the size range, the greater the size classification effect, making the material more unfavorable for separation according to density; and the narrower the size range, the more suitable the material becomes for separation.