Abstract: In order to solve the problem of rigid anchor connection when using plane beam element, an exact expression of non-linear tangent stiffness matrix is derived for the plane beam element with rigid arms by using co-rotational procedure and variational method and considering the characteristic movement and deformation under forces. The precise algorithm of unbalanced forces is proposed, the detailed calculation procedure is presented, and a computer program is developed. Geometric nonlinear analyses for plane beam structures with and without rigid arms are carried out to verify the reliability and computational efficiency of the proposed element formulation. The new element can be used in plane beam structures.