This paper presents numerical simulations of two-dimensional gas-solid fluidized beds by establishing the so-called particle-motion-resolved discrete model in which the motion of the solid phase is calculated by considering individual particle motions while gas flow is described by the Navier-Stokes equation. The particle-motion-resolved method is used to treat the interparticle interaction and particle/fluid interaction, resolving the overall movement of particles into the collision process accounting for the interparticle interaction and the suspension process related to the interaction with the fluid. It was assumed that momentum conservation of collision mechanics controls the interaction between colliding particles, while the state of each suspended particle is fully dominated by fluid/particle interaction. Comparing a two-dimensional hexagonal lattice with a three-dimensional hexagonal packed structure, an unreal porosity calculated on area basis is transformed into a three-dimensional porosity in order to give reasonable simulation results. The above model has been used for simulating bubbling, slugging and cluster behavior in gas-solid fluidization, resulting in more reasonable phenomena such as distinct eddies, particle-free slugs and the dynamic clusters.