Abstract: Clay particles in coal slurry water are unstable in nature and the parameters like size distribution, thickness of surface hydrated film and electric kinetic and Zeta potentials all tend to change with increase of soaking time, which can result in the change of the pattern of interaction between clay particles and the according change of interaction between coal and clay particles.The changes may lead finally to the variation of characteristics of sedimentation of coal slurry.A study is made in the paper with the representative clay minerals present in coal slurry water, kaolinite and montmorillonite, as the objects, with an aim to analyze the properties and change of behaviors of the clay minerals in water.Following an overview of the progress of the research work so far made both within and abroad on sedimentation characteristics based on clay behaviors, the paper looks ahead to the developing trend of such technologies for coal slurry water treatment.