A three-dimensional, two-phase, five-component mathematical model has been developed to describe flow characteristics of clay particles and flocs in the profile control process, in which the clay particle suspension is injected into the formation to react with residual polymer. This model considers the reaction of clay particles with residual polymer, apparent viscosity of the mixture, retention of clay particles and flocs, as well as the decline in porosity and permeability caused by the retention of clay particles and fl ocs. A finite difference method is used to discretize the equation for each component in the model. The Runge-Kutta method is used to solve the polymer flow equation, and operator splitting algorithms are used to split the fl ow equation for clay particles into a hyperbolic equation for convection and a parabolic equation for diffusion, which effectively ensures excellent precision, high speed and good stability. The numerical simulation had been applied successfully in the 4-P1920 unit of the Lamadian Oilfield to forecast the blocking capacity of clay particle suspension and to optimize the injection parameters.