The invention discloses a self-resetting tension-compression gas spring for variable stiffness. The gas spring comprises a cylinder tube, a transmission rod, inert gas, a middle spacer, a seal ring and connectors. The gas spring is characterized in that the inert gas adopted by the gas spring is less in pressure difference in the early stage of deformation, the pressure difference is increased along with increasing of deformation, the gas spring has the advantage that the stiffness is increased along with increasing of the external force, and the purposes of being small in deformation damping and high in deformation restriction are achieved; due to the fact that a cavity is filled with high pressure inert gas, the gas spring can recover automatically after external load is removed, the purpose of controlling the self-resetting speed is achieved, and the phenomenon that the structure vibrates is avoided. The steel structure bracket damping ratio can be effectively increased, and the problem that when the stiffness is improved, vibration is increased is solved.