Abstract: The United States Nuclear Regulatory Commission (USNRC) specifies the requirements of seismic time histories for the seismic design and analysis of nuclear power plants, in which the seismic time histories are either compatible with single-damping target response spectrum or with multi-damping target response spectra. In the seismic design and analysis of nuclear equipment and components, the seismic time history compatible with the multi-damping floor response spectra are required. Based on such engineering problem, this study proposed a method to generate the seismic time history compatible with the multi-damping floor response spectra. In this method, the Hilbert-Huang Transform (HHT) is used to modify the frequency and amplitude information of seed motions, yielding the spectrum-compatible seismic time histories that completely satisfy the requirements of USNRC standards. Consequently, this study provides suitable seismic excitation for seismic safety evaluation of nuclear equipment and components.