Various kinds of geo-disasters have occurred, such as soil avalanches, landslides, failure of river dike, liquefaction and scoring. These disasters have caused serious damage to infrastructures and human activities. Numerical simulations are one of the powerful tools for predicting (1) when the failure will take place, (2) where the failure take place, (3) how far the collapsed soil mass will flow, and (4) how large the impact force to structures will be. In this paper, FEM, CFD, DEM and SPH are introduced as numerical methods for costal geo-disasters. Brief explanation of theory of each numerical method will be described in this paper. Based on simulated results, advantages and disadvantages of different methods are discussed.