Abstract: To simulate accurately the complicated boundary conditions and overcome the problems caused by wide gap of scale between length and width,and change of computational boundary conditions as water-level variations,a 2D river-ice numerical model based upon the body-fitted method is developed by using the principles of hydrodynamics and thermodynamics and considering the influence of the frazil ice accumulating under ice cover and the shape of freezing fringe of ice cover during the river-ice process. The model is capable of determining the velocity field,the distribution of water temperature,the concentration distribution of the frazil ice,transportation of the floating ice,the progression,stability and thaw of ice cover and the transportation,accumulation and erosion of ice under ice cover MacCormack scheme is used to solve the equations.The model is validated through the field observations in Hequ reach of the Yellow river. The results show that the 2D numerical model presented is capable of simulating the river-ice process with accuracy.