Abstract: The seismic performance of low-rise cold-formed thin-walled steel buildings is good, it is not clear when the structural system changes from low-rise building to multi-story building. In addition, the seismic action increased with the increase of building height. Thus, to ensure the safety of multi-story cold-formed thin-walled steel structures, a definite seismic design method is necessary. In the paper, the damage structural parameters were determined and the damage criterion was established based on the results of existing shaking table tests of full-scale buildings, combined with tests of the double-layer composite wall and the joint of composite wall and floor. Furthermore, the simplified mechanical analysis model of the structure was established by using the equivalent rod method. The SAP 2000 was adopted to analyze the seismic performance of 4-6 stories structure, and the damage indexes and displacement angles of the structure under different rare earthquakes were obtained. Then, according to the damage criterion and the requirements of "three-level" seismic fortification, the seismic design of the structure was completed by adjusting the characteristic values of the restoring force skeleton curves. The main results were shown that: 1) under the action of 7 degree or 8 degree rare earthquakes, the structure appeared "medium damage" and the top displacement angle satisfied the limit value. Under the action of 9 degree rare earthquake, the interlayer displacement angle exceeded the limit value of "serious damage". Therefore, the interlayer strengthening was required to satisfy the requirements of "large earthquake no collapse" under large earthquake. 2) The seismic capacity of the structure could be improved by adding truss strengthening components to meet the seismic fortification requirements of the structure.