In this study, numerical simulation of suspended sediment transport was conducted on the basis of an equation of motion in mass point system. LES turbulence model was introduced to simulate a coherent structure of turbulent shear flow which is composed of a series of ejection and sweep. The motion of multiple sediment particles were computed in this flow field, and their trajectories were analyzed statistically. And then a diffusion coefficient of sediment was evaluated numerically on the basis of diffusion theory by Taylor (1953). It was found that the diffusion coefficient of sediments approaches to that of turbulence as the sediments continue to move. This result coincides with the assumption of traditional analysis.