Alternating　current　poling　(ACP)　is　an　effective　method　to　improve　the　piezoelectric　performance　of　relaxor-PbTiO3　(PT)　ferroelectric　single　crystal.　0.72Pb(Mg1/3Nb2/3)O3-0.28PbTiO3　(PMN-PT)　single　crystals　have　been　used　to　fabricate　piezoelectric　transducers　for　medical　imaging.　Up　to　date,　there　are　no　reports　about　the　full　matrix　material　constants　of　PMN-0.28PT　single　crystals　poled　by　ACP.　Here,　we　report　the　complete　sets　of　elastic,　dielectric,　and　piezoelectric　properties　of　[001]-poled　PMN-0.28PT　single　crystals　by　direct　current　poling　(DCP)　and　ACP　through　the　resonance　method.　The　results　show　that　[001]-poled　rhombohedral　PMN-0.28PT　single　crystals　exhibit　the　enhancement　of　longitudinal　and　transverse　piezoelectric　properties　(d33　∼　2000　pC/N,　d31}　∼　-1010　pC/N)　after　ACP.　Compared　with　DCP　samples　(d33　∼　1660　pC/N,　d31　∼　-780　pC/N),　the　values　of　d33　and　d31　increase　20%　and　29%,　respectively.　While　the　d15　value　decrease　from　110　pC/N　for　DCP　sample　to　90　pC/N　for　ACP　sample,　showing　the　decrease　in　transverse　shear　piezoelectric　properties.　In　addition,　the　elastic　stiffness　coefficients　c11　,　c12　,　c13　,　the　elastic　compliance　coefficients　s11　,　s12　,　and　the　dielectric　constants　varepsilon　11}　,　varepsilon　33　have　great　change　compared　with　DCP　and　ACP　samples.　This　variation　of　the　property　matrices　provides　a　reference　for　high-performance　piezoelectric　device　design.　©　1986-2012　IEEE.