The discrete element program PFC^3D was used for numerical simulation of a model experiment, which was carried out on an indoor vibration table, in order to study the fluidization of iron concentrate ore in bulk under dynamic loads. The evolution and internal mechanism of the iron concentrate ore fluidization was studied from a mesoscopic perspective. With consideration of the unsaturation during the fluidization process, the water was simulated with small granules and the matrix suction was simulated by setting a bond model between fine granules of ore. The change and development of the displacement field, water particle migration, and mesoscopic fabric were observed during the fluidization process. The results of numerical simulation were compared with those of the model experiment. It was found that the main cause of iron concentrate ore fluidization is the increase of the water level. The mesoscopic mechanisms of fluidization are as follows: under dynamic loads, the fine particles move downwards through the spaces between coarse particles, and the water between the particles that becomes water film flows upwards.