Abstract: A theoretical algorithm by using united Lagrangian-Eulerian (ULE) method for the deformation and stress of the clamped-clamped thin elastic plate in a continuous cross-flow of ideal fluid is presented. In this approach, material is described by relatively reasonable form (e.g., Lagrangian for solids, Eulerian for fluids, Lagrangian and Eulerian for the interfaces of them). Kinematic equation and dynamic equation of fluid-solid contact surfaces are established using united Lagrangian-Eulerian method. The deflection and stress of the thin elastic plate in continuous cross-flow of ideal fluid based united Lagrangian-Eulerian method and doublet theory are given. And the parameters’ effect on deflection and stress of elastic plate is presented. Theoretical results are compared with numerical solutions. It is shown that the united Lagrangian-Eulerian (ULE) method is an effective method for the problem of thin elastic plate in an ideal cross-flow.