Bubbling behaviors in the fluidized beds by soft-sphere method of the particle-motion-resolved discrete model were simulated in this paper. The influences of gas superficial velocity, restitution coefficient, structure of distributor, ratio of bed width and height, and distribution of particle diameters on the bubbling behaviors were studied. Numerical results indicate that the processes of bubble formation, rising and breaking are accelerated as the gas superficial velocity increasing. If the gas superficial velocity is too fast or too slow, the bubbling behaviors will be weakened. Restitution coefficient and structure of distributor have distinct influences on the bubbling behaviors. When the ratio of bed width and height is small, slugging phenomena will appear in fluidized beds. The smaller ratio of bed width and height, the more apparent of slugging phenomena .The distribution of particle diameters has little influence on the bubbling behaviors.