Based　on　46　project　data　of　evaluation　of　seismic　safety　for　the　Chinese　nuclear　power　plant　(NPP)　siting　and　construction　in　the　last　ten　years,　the　controlling　impacts　of　the　calculated　results　from　different　seismic　hazard　analysis　methods　are　analyzed　and　discussed　on　the　determination　of　the　site　specific　design　ground　motion　for　nuclear　power　plants,　and　statistic　analyses　are　made　on　the　results　calculated　by　the　probabilistic　seismic　hazard　analysis　method　and　the　results　induced　by　tectonic　earthquakes　and　diffuse　earthquakes　(diffuse　seismicity)　in　the　deterministic　seismic　hazard　analysis　method.　The　research　result　shows　that:　In　the　weaker　seismicity　area,　the　site　specific　design　ground　motion　parameters　are　mainly　controlled　by　the　calculated　results　from　the　deterministic　seismic　hazard　analysis　method,　especially　the　peak　ground　acceleration　(PGA)　and　high　frequency　spectral　accelerations　are　controlled　by　the　results　induced　by　the　diffuse　earthquake,　and　therefore,　the　NPP　construction　based　on　the　site　specific　design　ground　motion　in　the　area　will　have　higher　seismic　safety　margin;　In　relatively　strong　seismicity　area,　the　site　specific　design　ground　motion　parameters　are　more　likely　to　controlled　by　the　calculated　results　from　the　probabilistic　method,　and　for　some　NPP　sites,　the　ground　motion　parameters　from　probabilistic　method,　especially　the　low　frequency　spectral　accelerations　are　much　bigger　than　those　from　the　deterministic　method;　The　determination　of　site　specific　design　ground　motion　parameters　as　a　whole　is　very　conservative　for　Chinese　NPP　sites.