Abstract: Vortex ripple is widely formed in the coastal region,and the dynamics of vortex is responsible for the sediment transport In this paper,a 2-D Large-Eddy-Simulation method(LES)was used to predict the flow structure and the dynamics of vortex in the bot om layers under the action of the wave.The numerical simulation results show a complete process of vortex formation,evolvement and disappearance.The bed shear stress distribut ion and the length of the separation bubble with different scale vortex ripple also were studied.