The nonlinear second order differential equations are written about the second-order elastic analysis method theory,and the factors on seismic response of the steel frame are analyzed with the different dimensions of earthquake waves and damping.The result by MIDAS software shows that the influence of dimensions of earthquake wave including unidirectional earthquake wave and bidirectional earthquake waves and damping ratio could be affected greatly when analyzing the elastic time history for the frequent earthquake,and when analyzing the elastic-plastic time history for the unusual earthquake.Detailed suggestions for choose these influencing factors are provided.