According to the characteristics of long-period ground motions (GMs), 139 long-period GM records are selected to study the influence of structural dynamic parameters and long-period GM characteristics on the inelastic response spectra of long-period GMs. The following conclusions are obtained: compared with conventional GMs, the influence of the restoring force model and the post-yield stiffness ratio ( η ) on the spectral values of the medium- and long- periods of inelastic response spectra is larger, and the amplification effect of site soil on the inelastic response spectra is more significant; on the contrary, the effects of damping ratio ( ξ ) and displacement ductility ratio ( μ ) on the inelastic response spectra of conventional and long-period GMs are similar. Therefore, when establishing the design spectra of long-period GMs, it is necessary to select a reasonable restoring force model and η , while the existing influence law of ξ and μ on the conventional GM response spectra can be referred to, and the corresponding design spectra should be established according to different types of site soil; moreover, the design spectra of long-period GMs of a standard fortification intensity can be established first, and then the design spectra of other fortification intensities can be adjusted by the ratio of PGAfortification and PGAstandard.