Air and particle motions in a group-B particle turbulent fluidized bed are numerically simulated. The locally averaged three-dimensional Navier-Stokes equations and the Lagrangian particle equations, in which the mutual interactions between air and particles and the two-body collisions between particles were taken into account. were simultaneously solved. Reynolds stress terms and the turbulent mass flux terms caused by the subgrid scale fluctuations have been modeled by the large eddy simulation in which the effect of particle existence on subgrid scale flows has been taken into account. The corresponding experiments were also performed. It is found that calculated results well represent the experimental instantaneous particle positions and flow characteristics of the air and particles, and enable us to know the mechanisms of various phenomena such as the large complex bubbling flow and the particle cluster formation.