PZT　based　multi-system　has　shown　super　piezoelectric　properties　when　the　composition　was　located　at　morphotropic　phase　boundary　(MPB),　which　divided　the　regions　into　rhombohedral　and　tetragonal　structures　equally.　In　the　present　paper,　the　diffuse　phase　transition　and　phase　coexistence　of　rhombohedral　and　tetragonal　phases　of　0.5PZN-0.5PZT　ceramics　were　investigated　by　Raman　scattering　spectroscopy　in　detail.　The　results　revealed　that　compared　with　pure　PZT,　the　width　of　Raman　bands　of　0.5PZN-0.5PZT　was　quite　broad,　indicating　that　the　system　has　strong　relaxor　feature.　According　to　the　temperature　dependence　of　dielectric　permittivity,　the　indicator　of　degree　of　diffuseness,　gamma,　was　calculated　and　the　values　were　as　high　as　1.71.　Through　the　separation　by　Gauss　fitting　of　the　Raman　bands,　the　intensities　of　different　Raman　vibration　modes,　such　as　the　tetragonal　E(3TO),　A(1)(3TO),　E(4LO)　and　A(1)(3LO)　modes,　as　well　as　the　rhombohedral　R-1　and　R-h　modes,　were　determined.　The　results　indicated　that　for　0.5PZN-0.5PZT　system,　the　fraction　of　rhombohedral　phase　was　equal　to　the　tetragonal　phase,　which　has　also　been　affirmed　by　XRD　results　and　suggested　that　the　system　was　close　to　the　MPB.　Excellent　piezoelectric　properties,　such　as　k(p)　(0.66)　and　d(33)　(425　pC/N),　were　found　in　0.5PZN-0.5PZT　system,　showing　a　great　promise　of　this　system　as　practical　materials　for　piezoelectric　actuators.