The pushover method was applied to analyze the anti-earthquake performances of the knee bracing steel frame under three kind rare earthquake intensities,The failure mode and plasticity hinge developing processing under the rare earthquake function of the cross truss system were obtained,and the structure has been assessed the anti-earthquake performances under the different earthquakes.Under the earthquake plasticity hinges appear from knee brace to ordinary brace the last is on the beam,it can consume earthquake energy to protect the column being destroyed at the same time.The result indicates the knee bracing steel frame adjust to the requirement of strong column and weak beam.