In this study, the structural, dielectric and piezoelectric properties of $Pb[(Ni_{1/3}Nb_{2/3})_x-(Mn_{1/3}Nb_{2/3})_{0.09-x}-(Zn_{0.505}Ti_{0.495)_0.91]O_3$ (x=0, 0.01, 0.02, 0.03, 0.04, 0.05) system ceramics were investigated to develop the composition ceramics for piezoelectric transformer. All the specimens were sintered at $1250^{circ}C$ and its physical properties were measured, and the results are as follows : With increasing PNN substitution for PMN-PZT system, dielectric constant was increased and electro-mechanical coupling factor($k_p$) was increased to 0.62 at 5 mol% while mechanical quality factor(Qm) was decreased.