The phase transformation and thermal expansion behaviour of (Pb0.97La 0.02(Zr0.65Sn0.35-xTix)O3 (PZST,0.1≤x≤0.14)antiferroelectric ceramics (AFEt)have been investigated as functions of temperature and Ti conte nt x.It was found that for the specimens with 0.1≤x≤0.12,the thermal expansion coefficient (α) curve showed an unusual “bending” at the temperature of T,wh ile the specimens remained a tetragonal phase.For 0.125≤x≤0.14,the specimens s howed a ferroelectric rhombohedral phase (FER) at room temperature.Wh en heated ,the FER phase was changed to an antiferroelectric tetragonal phase ( AFEt) a nd pareoelectroic cubic phase (PEc) at temperatures of TFA and Tc,resp ectively.In addition,T and TFA increased with the increase of Ti cont ent x , while Tc was decreased.The phases were detected by the XRD pattern at differ ent temperatures.The temperature-Ti content (x) phase diagram of (Pb0.97La 0.02)(Zr0.65Sn0.35-xTix)O3 was finally established.The the rmal expansion behaviour of (Pb0.97La0.02)(Zr0.65Sn0.35-xTix)O3 (0.1≤x≤0.14) have been expla ined based upon the nano-size phase s eparation of the PZST complex pervoskite compounds.