Colloidal properties of clay minerals may have some effects on the rheology and plasticity in the claywater system.It is well known that clay minerals have very complicated properties from the crystallochemical standpoints. The intricated movements of clay particles in water, however, may not be revealed enough by the only analysis of their mineralogical properties. The present report deals with that the clay minerals are supposed to be one simple plate and the particle associations of clay suspensions are analysed on the basis of newly developed DLVO theory.