A one-phase model is established by using CFD(Computational Fluid Dynamics) software,which includes a hydrodynamic sub-model,an erosion-deposition and a moving boundary method.in the model,the velocity field surrounding obstacles on the seabed is computed by a three dimensional k-εturbulence closure sub-model.Erosion and deposition caused by the transportation of suspended load and bed load are also calculated.The evolution of bedform is simulated in a mobile grid technipue.The three-dimensional flow pattems and evolution of bedform around three different obstacles are simulated using the one-phase model.The hydrodynamic process and sediment transportation process surrounding the obstacles are reproduced in detail. The simuated results of bedform evolution are in good agreement with laboratory measurement results in 2005.