PLZST antiferroelectric ceramics were synthesized by the modified coprecipitation method. Effect of variations in the Ti4+:Sn4+ ratio on phase and properties were evaluated. The XRD patterns show that with the increasing of Ti4+ content, the structure of ceramics changes from tetragonal phase to rhombohedral phase and this was certified by the P-E hysteresis loops. The temperature dependence of dielectric constant of the ceramics was measured. Low frequency dispersion at room temperature disappeared when the temperature increased and the variation of T-m is not linear with the content of Ti4+. These unusual behaviors had been interpreted.