Abstract: In order to investigate the mechanical behavior of concrete filled RHS (rectangular hollow section) beams and the seismic behavior of concrete filled RHS frames, two one-bay, two-story concrete-filled RHS frame specimens are tested under static vertical loads and low cycle horizontal loads. Taking the steel ratio of column cross-section as the main experimental parameter, hysteretic behavior, ductility, degradation of strength and stiffness are examined and analyzed. The result indicates that the concrete-filled RHS frames have advantages such as higher bearing capacity, excellent energy dissipation capacity and ductility behavior, and inconspicuous strength degradation compared with the reinforced concrete frame and the steel frame. Therefore, it is concluded that the concrete-filled RHS frame has wonderful superiority on bearing capacity, seismic behavior and effective use of material; it deserves further research and wide application.