Pb(Zn1/3Ni2/3)c(Ni1/3Nb2/3)a(ZrxTiy)bO3 (PZN–PNN–PZT, the ratios of PNN/PZT a/b were 0.88, 1 and 1.136) piezoelectric ceramics were prepared by a traditional solid-state reaction method. The effects of PNN/PZT ratio on phase structure, microstructure and electric properties as well as the relaxation behaviors of PZN–PNN–PZT ceramics were investigated. The XRD patterns showed that all ceramics samples had a pure perovskite phase structure. Meanwhile, it was found that the phase structure undergoes a tetragonal, tetragonal-rhombohedral to rhombohedral transition as ratios of PNN/PZT increased. With the increasing of a/b from 0.88 to 1.136, the dielectric constant and diffusive phase coefficient decreases, it was indicated that relaxation behaviors also decreased. When ceramics with a/b was 1.136, the dielectric relaxation γ reached the minimum and electrical properties were poor. The electric properties of ceramics with a/b was 1.00 have an excellent properties, it was indicated that ceramics reached an optimization at the MPB structure.