Reactor plant structures in nuclear power plants must withstand the high temperatures and pressures generated during nuclear reactions and potential seismic impact. Due to its excellent lateral stiffness and buckling resistance, the concrete-filled double-skin steel tubular (CFDST) structure can effectively prevent structural damage caused by high temperature, high pressure, and vibration, and ensure the integrity of the plant throughout its service life. However, in the engineering application of CFDST to reactor pressure vessels, the seismic behavior of CFDST columns characterized by large structural scale, high hollow ratio, and low steel ratio has not been fully stressed. In this study, two 1/8-scaled specimens of CFDST are designed for cyclic loading tests. The hysteresis curves, skeleton curve, and energy dissipation capacity were analyzed, and the effects of axial compression ratio on the seismic behavior of the structure were investigated. The test shows that CFDST has high ultimate capacity and good deformation ability due to the composite action of steel tubes and concrete.