Abstract. In this paper, we introduce the Hamiltonian system to study bending problems of elastic cantilever-beam. The variational method and the variable seperation method are employed to establish the dual governing equations. Due to the completeness property of the eigenvectors, the solution can be expressed by the linear combination of these eigenvectors, and the coefficients of the combination are determined by the boundary conditions. In the numerical results, stress distributions of bending deformation are discussed.