The spur dike is a common structure controlling river flow in channel regulation,around which the flow is characterized by strong turbulence.Comparing with the time-averaged models based on Reynolds equation,the large eddy simulation (LES) has a stronger capability to perform the eddy.The sub-grid-scale (SGS) model,one of LES,is introduced into 2-D river flow model under the Cartesian coordinate to filter the governing equations utilizing the box filter method.The large eddy is computed directly,while the small one is computed with the SGS model by Smagorinsky.The square grid and ADI algorithm is used to discretize the governing equations.The application of the model to simulation of river circumfluence around a non-submerged spur dike shows that the calculated eddies and depth distribution of turbulent flow are in accordance with the observation data and the precision satisfies the engineering requirements.