Abstract: Pb (Zn_1/3Nb_2/3)O₃-Ba(Zn_1/3Nb_2/3)O₃ （PZN-BZN） and Pb(Zn_1/3Nb_2/3O₃-BaTiO₃（PZN-BT） relaxor ferroelectric ceramics were prepared by conventional ceramic processing routes. The dielectric properties of PZN-BZN and PZN-BT ceramics as well as the effects of heat treatment on dielectric property for PZN-based ceramics were systematically investigated. Pure perovskite phase was obtained in composition 0.9PZN-0.1BZN by solid-state reaction method. The maximal dielectrie constant K_m of 0.9PZN-0.1BZN ceramics reaches 6160（lkHz）. Comparing dielectric properties of PZN-BZN and PZN-BT ceramics, it is found that BZN is an implicit component for PZN-BT system. The non-polar BZN component might make a notable impact on dielectric properties of PZNBT ceramics. The K_m of the all compositions increases after annealing, but heat treatment cannot change the relaxor characteristic of PZN-BZN and PZN-BT systems.