The paper presents some results about the impacts of sand mining to river bank stability in Tien river, Co Chien river (downstream of My Thuan bridge) by using numerical model. In this research, the authors used twodimensional (2D) hydrodynamic model and Geo-slope software in order to calculate the river bank erosion for three scenarios: no sand mining, regular sand mining and irregular sand mining. These obtained results show that the sand mining activities have positive and negative impacts. Regular sand mining will contribute to minimize erosion. In contrast, it will caused hydrodynamic changes leading to unpredictable risk of landslides.