Abstract: The equilibrium differential equations of finite long beams on an elastic foundation under an arbitrary symmetrical load were proposed on the basis of the horizontal friction being direct proportion to the supporting force. By utilizing the Galerkin integral method and adopting the model functions of displacements, the nonlinear algebraic equations are founded. Solving the nonlinear algebraic equations by an iterative method, the solutions of the internal force and displacements are obtained. By an example, it is founded that the horizontal friction has a less influence on the deflection and shearing force but it has a greatly influence on the bending moment and axial force of the beam. It is necessary that the horizontal friction is considered while strength of the beam on elastic foundation is analyzed.