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A new numerical model of sand-wind interaction was proposed to predict the surface morphology evolution and provide the basis for dimension design of sand barrier. Based on the theory of probability and statistics, the model realized sand-wind interaction process by calculating wind erosion and deposition probability of sand grains at different wind speeds. Firstly, the model parameters of air phase and sand phase were initialized, and the velocity distribution can be calculated by computational fluid dynamic (CFD) method. Secondly, the wind friction velocity of sand element was calculated by using velocity field data, and the sand transport rate can be obtained. Finally, the thickness of sand element was calculated by calculating sand change in one time step. The moving mesh technique was used to change the fluctuation of the sand bed by changing the coordinates of lower boundary nodes. The numerical results were compared with the measured results, which showed that the numerical results of the surface morphology in the sand barrier were close to the measured results. The lowest point of pit was the maximum position that moved along the downwind area, the average absolute error was 17.86% when t=4d, the error was decreased gradually with the increase of sand accumulation, the average absolute error was 8.52% when t=8d. Both qualitative and quantitative results were consistent with the measured results, and the model can simulate the surface morphology evolution of sand barrier correctly.