The rheological behavior of kaolin and montmorillonite suspensions at low concentrations in water and polymer solutions has been investigated. An influence of the polymer concentration on the viscosity of suspension for the kaolin suspension in the presence of diethylenetriaminomethylated polyacrylamide and for the montmorillonite suspension in the presence of polyacrylic acid has been demonstrated. The dependence between the shear stress and the cross-sectional area of particles and the number of particles in a unit volume of the suspension has been shown. Mathematical equations for the number of aggregates in the unit volume of suspension and the number of initial particles in aggregate at the different polymer concentrations in mixture are proposed.