Relaxor　ferroelectric　Pb(Sc0.5Nb0.5)O-3　ceramics　were　synthesized　by　a　modified　solid　oxide　reaction　method.　The　x-ray　diffraction　and　Raman　scattering　analysis　affirmed　that　annealing　dominated　the　ordering　degree　of　PSN　samples.　The　measurements　on　dielectric　response　and　ferroelectric　behavior　indicate　the　prominent　impact　of　the　ordering　degree.　The　dielectric　response　of　a　relaxor　ferroelectric　is　determined　by　the　growing　and　freezing　behaviors　of　the　polar　regions,　which　is　correlated　with　the　ordering　degree.　In　addition,　the　behavior　of　the　ferroelectric　phase　transition　was　controlled　by　the　lattice　distortion　in　ordered　domain　due　to　the　displacement　of　Pb　and　ferroelectrically　active　Nb　cations　in　the　PSN　lattice.　(C)　2008　American　Institute　of　Physics.