Based　on　the　engineering　geological　data　of　a　nuclear　power　plant　site,　nine　engineering　geological　profiles　were　created　with　hard　interlayers　of　different　thicknesses.　The　equivalent　linearization　method　of　seismic　motion　segment-input　used　for　one-dimensional　nonlinear　seismic　response　analysis　was　applied　to　study　the　effect　of　the　interlayer　thickness　on　the　peak　acceleration　and　the　acceleration　response　spectra　of　the　site　seismic　response.　The　results　showed　that　there　was　an　obvious　influence　of　hard　interlayer　thickness　on　site　seismic　responses.　With　the　increase　of　hard　interlayer　thickness,　the　site　nonlinear　effect　on　seismic　responses　decreased.　Under　the　same　thickness　of　the　hard　interlayer,　the　nonlinear　effect　of　the　site　was　strengthened　with　the　higher　input　peak　acceleration.　In　addition,　the　short-period　acceleration　response　spectrum　was　found　to　be　significantly　influenced　by　the　hard　interlayer　and　showed　that　the　longer　the　period,　the　less　influence　of　the　hard　interlayer　on　the　acceleration　response　spectrum　coordinates.　Moreover,　the　influenced　frequency　band　was　wider　with　the　increase　in　the　thickness　of　hard　interlayer.