This paper describes computations of dune formations in rivers by DEM-URANS coupling approach. In the present model, complicated turbulent flow structure on dunes was simulated by an Euler type vertical 2D flow model with a non-linear k-e turbulence model. The motions of sand particles were simulated by a Lagrange type approach utilizing the distinct element method (DEM). Dune formations have been successfully simulated by Sekine(2001). Sekine (2001) successfully simulated dune process for the first time using Lagrangian numerical approach called saltation model. On the other hand, the present model replicates each particle’s behavior including separation, collision and holding utilizing more physically based model. The computational result shows that the present method can capture reasonably the fundamental process of dune formation.