Abstract: In this paper,a degenerated beam element is developed,evolving from a bilinear degenerated shell element.Under the assumption of plane section,the 3D displacement field equation is discretized in terms of nodal displacements.The strain-displacement equations and constitutive equations of 3D structure are utilized in the formulation of the element.A FEM program has been developed.Several examples are tested to demonstrate the effectiveness,accuracy and versatility of this element.It is also shown that the element is applicable in the non-linear finite element analysis of complicated structures.