In performance assessment of geological disposal systems the phenomenon of dispersion in geological media is one of the most important processes to be modeled and is dependent on the heterogeneity of the media. In order to understand the dispersion process in a well defined heterogeneous field, laboratory experimental apparatus, named MACRO, was constructed to study fluid flow and mass transport. A synthetic heterogeneous field was constructed in a flow-bed using six kinds of glass beads with diameters of 0.1, 0.15, 0.2, 0.4, 0.6 and 0.8 mm. Both dye (brilliant blue) and NaCI solution were used as tracers in the experiment. A particle tracking method, considering advection, was used in numerical simulations of the experiment, and the dispersion effect was assumed to be expressed by the variability of the local advective velocity in a high resolution numerical grid. The simulated results obtained by the particle tracking method agreed with the measurement, confirming the applicability of modelling approach used in this study.