A　Pb1-xSrx(Zn1/3Nb2/3)(0.2)(Zr0.5Ti0.5)(0.8)O-3　(P(1-x)S(x)ZNZT,　0.00　＜=　x　＜=　0.10)　system　was　prepared　through　a　conventional　solid　oxide　process.　Increasing　addition　of　Sr2+　was　found　to　induce　a　continuous　decrease　in　grain　size　from　2.46　mu　m　to　1.14　mu　m,　accompanied　by　a　phase　transformation　from　coexisting　rhombohedral　and　tetragonal　phases　to　tetragonal　phase　only.　The　underlying　mechanism　of　the　evolution　of　dielectric　and　ferroelectric　behavior　in　the　P(1-x)S(x)ZNZT　ferroelectric　ceramics　was　ascribed　to　the　synergy　between　the　grain　size　effect　and　the　dilution　of　Pb-O　covalency.　Additionally,　the　grain　size　effect　on　domain　wall　displacement　was　found　to　be　the　main　origin　of　the　superior　permittivity　and　piezoelectricity　of　the　ceramics　at　intermediate　grain　size.　The　optimal　electrical　properties　achieved　for　the　P(0.95)S(0.05)ZNZT　specimen　at　a　grain　size　of　about　1.79　mu　m,　d(33)　=　465　pC/N,　d(33)　x　g(33)　=　11　047　x　10(-15)　m(2)/N　make　this　material　promising　for　multilayer　energy　harvesting　device　applications.　Published　by　AIP　Publishing.