Abstract: With the features of light weight, high strength, good seismic performance and easy assembly, steel structure is one of the most ideal residences, and it has made great development in recent years under the advocacy of national and local policies. Traditional steel structure residential mainly adopts steel frame structure, steel frame support structure, steel frame shear wall structure, etc. However, these structural systems generally have the problem of “convex beams and columns”, which affects the use of building space and living experience. For this reason, this paper proposes a kind of a steel frame ftructure with flat steel tubular column and X-type brace on the basis of traditional steel frame structure, which adopts flat steel tube columns with cross-section width of 200 mm or less and narrow flange steel beams, and increases the lateral stiffness of the structure through the setting of X-type support, which can solve the problem of “convex beams and columns” better. For this new structural system, the following work is carried out in this paper: 1) PKPM structural design software is used to analyze the structural mechanical performance and overall index of a student dormitory building which adopts flat steel tubular column X-type supported steel frame structure and traditional steel frame structure respectively under multiple earthquakes, including the structural period, the maximum interstory displacement angle and the minimum stiffness ratio of the structure under earthquake action, and the steel amount used in the two structural systems is compared. 2) Elastic-plastic analysis of the structural system under rare earthquakes was carried out by selecting two natural seismic waves and one artificial seismic wave using SAUSAGE software, and the elastic-plastic interlayer displacement angle and member performance level of the structure under each seismic condition were statistically analyzed. 3) the static pushover analysis of the basic structural units of the system was carried out by using MIDAS FEA finite element software, and its failure mode and ductility performance were analyzed. The research results show that: 1) Through the reasonable arrangement of flat steel tubular column X-type support unit, the structure meets the requirements of the Code for Seismic Design of Building (GB 50011—2010) under the action of multiple earthquakes, and has a certain economy, and the steel consumption is saved about 3% compared with the traditional steel frame structure. 2) The structure shows good seismic performance under rare earthquakes, and most of the components are not damaged above moderate level, and the maximum elasticplastic interlayer displacement angle of the structure under each working condition is less than 1/ 50, which meets the code GB 50011— 2010. 3) Through the static finite element pushover analysis, the calculation of the structural displacement ductility coefficient is 8. 5, which indicates that the structure has good ductility and pushover resistance, at the same time, it can be seen that the column has more obvious damage in the part connected with the support, so the subsequent strengthening construction measures can be carried out for this part.