The dielectric behaviors of Pb(Zn 1/3Nb 2/3)O 3-PbTiO 3-BaTiO 3 (PZN-PT-BT) relaxor ferroelectric ceramics of several compositions have been investigated under high alternating electric field. In the broad temperature range of the diffuse phase transition, they show highly induced polarization. An unusual linear relation of the polarization with electrical field has been observed near the central portion of the hysteresis loops of some PZN-PT-BT ceramics, which is both temperature and composition dependent. The corresponding dielectric constants are fairly high as well. Moreover, a strong annealing effect is found in its dielectric response. The observed dielectric and ferroelectric properties may be understood using a proposed model of implicit Ba(Zn 1/3Nb 2/3)O 3 paraelectric nanoregions in PZN-PT-BT ceramics.