The mega debris flow that occurred on 13 August 2010 in Zoumaling Valley in Mianzhu County, China has done great damage to the local inhabitants, as well as to the re-construction projects in the quake-hit areas. Moreover, it is of high possibility that a secondary disaster would reappear and result in worse consequences. In order to maximize risk reduction of this problem, the local government planned to construct seven debris-resisting barriers across each ditch for mitigation of debris flow hazards in the future. In this paper, the numerical simulation fields of flow velocity, pressure, and mud depth of the Zoumaling debris flow had been computed by using finite volume method software based on computational fluid dynamics (CFD). The Bingham fluid was chosen as the constitutive model of this debris flow. The debris flow geometry model was a 3D model. The initial conditions, boundary conditions, control equations, and parameters were determined and adjusted by the actual conditions and analyses. The flow field data obtained from numerical simulations were substituted into the finite element software ANSYS. Then the calculations of fluid-solid coupling action between the flow and dam had been done. All these results of simulations and analyses could be the guide and suggestion for the design and construction of prevention engineering of Zoumaling debris flow.