Minimum fluidization velocity is one of the most important parameters when characterizing the hydrodynamics of a fluidized bed. Experiment studies on the effects of bed height and material density on the minimum fluidization velocity for inverse fluidization beds. Were carried out using a 10 cm diameter cylinder fluidized bed. Two types of particles were tested polyethylene (PE) and polypropylene (PP) bead, each with a density of 966.6, 877.3, 896.4, or 846.2 kg/m3, respectively, Results show that minimum fluidization velocity for tow tested materials was insensitive to bed height and increased with increasing the material density. The minimum fluidization velocity was correlated with dimensionless groups and independent parameters with correlation coefficient is 0.9389.