In order to solve the calculation problems of the curved beam, an arbitrary crosssection beam and composite beam, a degenerated 3D fiber beam element is derived based on the degenerated theory. According to the basic assumption of plane section, the 3D displacement field equations of an arbitrary point are discretized in terms of nodal displacements, which take account of shear deformation effect. Furthermore, the tangent stiffness matrix formulation, which takes geometric and material nonlinearity into account, is deduced using Update Lagrange formulation. A finite element method program has been developed, and several typical examples are tested to demonstrate the effectiveness, accuracy and versatility of this beam element.