Abstract: To investigate the seismic behavior of the steel-concrete composite frame structure system,a 4 polyline plastic hinge model of the composite beam is suggested for the elastic-plastic analysis of the composite frame.And the analytic models of CB-CFST,SB-CFST,CB-ETRC,SB-ETRC and RC frame structures are separately created.Then the mode analysis,spectrum and the elastic time history analysis under frequent earthquake,elastic-plastic analysis under server earthquake of these structures are carried out.Resultsillustrate that compared with SB-CFST,the integral stiffness of CB-CFST is enhanced;natural periods are shortened;displacement responses are decreased overall.Compared with the CB-RC frame,under rare earthquakes,RC columns can not satisfy the demand of“no collapsing with strong earthquake”.And after increasing dimensions and reinforcement ratios of columns,the plastic hinge is also found at the end of columns.