Abstract: A new finite element method, which is the characteristic-based operator-splitting (CBOS) algorithm, is adopted to solve Navier-Stokes (N-S) equations. In each time step, the equations are split into a diffusive part and a convective part. The convective part is discretized using the characteristic Galerkin method and solved explicitly. The moving interface is captured by the pseudo-concentration method, thus, a new wave model is established. Through the validation of dam break failure onto a downstream dry bed or a wet bed, it is shown that the present model can accurately simulate the generation and the transmission of the dam breaking flow. We also study the evolution characteristics of the free surface in the dry bed case. Meanwhile, the generation of surge waves and the formation of curling waves are discussed for the wet bed case. In addition, it is analyzed that the pressure of the downstream bed suddenly increases under the impact of the surge waves on the water body of the downstream wet bed.