Fluid catalytic cracking(FCC) plays an important role in the processes of the heavy oil refining industry. A thoroughly understanding of fluid characteristics in the gas-solid fluidized beds is helpful for designing the FCC units. A new two-fluid model developed by Brandani S and Zhang K is used to numerically investigate the hydrodynamics of FCC particles in the platform of CFX 4.4, a commercial CFD software package. Simulation is carried out in a two-dimensional fluidized bed with 0.25 m in width and 0.70 m in height. The particle with a diameter of 6.4×10- ⁵m and a density of 1 225 kg/m ³ is employed as solid phase. Two typical kinds of fluid dynamics, i.e., homogeneous fluidization and aggregative fluidization, are obtained under corresponding to superficial gas velocities, which are in good agreement with classical theories as well as experimental dates from the literatures.