Special-shaped column composed of concrete-filled square steel tubes(the SCFST column) braced frame has broad prospects of applications in high-rise steel structure residence for the reason that it represents considerable lateral stiffness, good seismic performance and outstanding architecture effect. Quasi-static tests were conducted to explore the seismic behavior mechanism, and beams and columns were destroyed in turn. The hysteretic curves of the structure were diamond-shaped with no pinch phenomenon, which illustrated that the structure performed well in energy dissipation. The structure had good ductility and seismic behavior in that the skeleton curve declined slowly. The finite element (FE) numerical simulation agreed well with the experimental result, verifying the correctness of the FE model. The restoring force model of the SCFST column-steel beam braced frame took axial compression ratio, the section of the column and the stiffness of the brace as main research factors. By linear regression analysis, the trilinear skeleton model was established which showed the hysteretic behavior and stiffness degradation of the SCFST column braced frame. As seen by from the comparison of the results of the model with those of the experiment, the skeleton curves of the model and the experiment were nearly the same, both of the hysteretic curves were in the shape of a parallelogram,and the anastomosis degree was high. In conclusions the restoring force model is an effective way to simulate the behavior of the frame and it can present the load displacement curve of the SCFST column braced frame under low reversed cyclic loading.