The three-dimensional space model of the steel frame and the braced steel frame were established for studying the lateral resistant performance of small-tall steel structure residence.The two models' dynamic analysis and time-history analysis on the 7 and 8 degree earthquake intensity were studied by using finite elements software.The two models' the relation of the coping displacement and relative storm displacement were compared,and the seismic performance of setting steel-brace on the practical engineering was proposed.