Abstract: The origin and application of structural performance factors were briefly introduced. Research results on the structural performance factors in single-degree-of-freedon (SDOF) systems was presented, related applications in seismic design codes of Europe, the United States, Australia, New Zealand, Mexico, Chile, and China’s Taiwan region were introduced, they all use smaller performance factor for short periods. Based on research results of past two decades, formulas consistent with the response spectra in current seismic codes of China were proposed to improve the practice of Chinese seismic design. Compared with various international seismic codes, the new proposal was suggested to extend the range of application of the equal displacement law to the equal displacement stage of the elastic response spectrum, therefore it would be the most conservative.