The physical properties of 0.5PZT-0.5(PNN-PZN) ceramics have been investigated as a function of PZN content. A pyrochlore phase exists in the range of 600∼850$^{circ}C$ and a stable perovskite phase appears above 850$^{circ}C$. The piezoelectric properties (except electro-mechanical coupling factor) of 0.5PZT-0.5(PNN-PZN) ceramics showed almost linear relationships of PZN content within the range of 0.5PZT-0.5PNN system and 0.5PZT-0.5PZN system. The temperature dependence of piezoelectric constant, the electric field dependence of induced strain and a bend strength are improved by addition of PZN.