This paper presents simulation results of the density segregation in a dense binary gas fluidized bed using a multi-fluid model from Chao et al. (2011). The segregation behavior of two types of particles with approximately same particle diameters and different particle densities was studied and validated using the experimental data from Formisani et al. (2008). Some detailed information regarding the gas, particle velocity profiles, the distributions of the particle volume fractions and the flotsam-to-total par- ticle volume fraction ratios is presented. The simulation results show that the simulated axial average flotsam-to-total particle volume fraction ratio distribution agrees reasonably with the experimental data of Formisani et al. (2008). The binary particle velocities are closely coupled though the segregation exists. The segregation behavior and the particle velocity profiles are superficial gas velocity dependent. The number and distribution of particle velocity vortices change dramatically with superficial gas velocity: at a comparatively low superficial gas velocity, the particles mainly segregate axially, and at a comparatively high superficial gas velocity, the particles segregate both axially and radially. This paper presents simulation results of the density segregation in a dense binary gas fluidized bed using a multi-fluid model from Chao et al. (2011). The segregation behavior of two types of particles with approximately same particle diameters and different particle densities was studied and validated using the experimental data from Formisani et al. (2008). Some detailed information regarding the gas, particle velocity profiles, the distributions of the particle volume fraction and the flotsam-to-total paricle volume fraction ratios presented. simulation results show that the simulated axial average flotsam-to-total particle volume fraction ratio distribution agrees reasonably with the experimental data of Formisani et al. (2008). The binary particle velocities are closely coupled though the segregation exists. The segregation behavior and the particle velocity profiles are superficial gas velocity dependent. The number and distribution of particle velocity vortices chan ge dramatic with superficial gas velocity: at a comparatively low superficial gas velocity, the particles mainly segregate axially, and at a comparatively high superficial gas velocity, the particles segregate both axially and radially.