A gas-solid bubbling fluidized bed was analyzed by using a discrete hard sphere particle model (DPM). Simulation results were validated by matching them to the results of the previous study. Particle translational and rotational characteristics were investigated in terms of gravities to find out their influences on the particle behaviors. The gravity did not significantly affect the particle macro-scale characteristics, such as particle translational velocity and rotational velocity, but acted an important role in particle micro-scale characteristics like granular temperatures. Particularly, the change of gravity affected the change of the bubble behavior and the particles' pulsation movement, which could lead to the transformation of the overall fluidized state. (C) 2014 Elsevier B.V. All rights reserved.