To investigate the static elasto-plastic properties of tensegrity structures，an efficient finite element me- thod—co-rotational ( CＲ) formulation，which is suitable to solve large rotation and small strain problems，was in- troduced． Large displacement of a space rod element was decomposed into a rigid body motion in the global coordi- nate system and a pure small deformation in the local coordinate system． A new form of tangent stiffness matrix was derived based on the proposed approach． An incremental-iterative solution strategy in conjunction with the Newton- Ｒaphson method was employed to study the geometrical nonlinear elasto-plastic properties of a quadruplex tensegrity unit． Ｒesearch results shows that the CＲ approach is computationally more efficient than the traditional TL and UL formulations． The rigidity of lower“fibers”is larger than that of upper“fibers”in the quadruplex unit． With the increase of the self-stress coefficient，the tensegrity unit becomes stiffer，and this is more obvious when the struc- ture is under compression than under tension． Compared with the elasto-plastic response of structure，the self-stress coefficient plays a more important role in elastic responses．