Coarse coal slurry has larger particle size, the effect of separation is poorer than that of fine slime, and it exerts a greater influence on coal preparation process. On the basis of the test result of raw coal, the adaptation effect of top water quantity on coarse slime was analyzed, and the top water quantity should be kept at about 0.75m3/h, the influence of flow channel and feed quantity on the separation effect were studied systematically. It was considered that the feed amount should be controlled at a lower level during the coarse slime separation and the size of the medium flow channel should be 6 mm.