Migration of colloids in porous media has been mainly studied using laboratory column experiments and simulation of breakthrough curve. In recent years, visualization experiments using micromodels have been increasingly used to make direct observations of colloid retention and transport behavior in porous media. In this study, we present a numerical method to simulate colloid retention and transport in systems comparable to visualization experiments. A 2-D particle tracking model programmed with FORTRAN has been developed to predict colloid transport in saturated porous media. Colloids are introduced to the domain after the flow driven by a constant pressure gradient is completely developed. The model considers Stokes drag force, Brownian force, colloid-grain and colloid-colloid interaction forces (including electrostatic double layer, van der Waals, and acid-base forces) on every single colloid and predicts moving trajectory and deposition of each colloid in the domain. The equations are solved numerically with the Adams-Bashforth-Moulton method. Effects of hydrodynamics and solution chemistry are examined by changing flow velocity and solution components. The model serves as a mechanistic basis for predicting colloid transport in porous media and is tested by conducting comparable micromodel visualization experiments.