Th doped PbTiO3 (PT) thin films with (001)/(100) preferred orientation are prepared by sol-gel method. High (100) oriented Pb0.4Sr0.6 (Ti0.97Mg0.03)O-2.97(PST) thin films are then deposited on the Th doped PbTiO3 inducing layer by rf-sputtering technique. The crystalline phase structure and orientation of the thin film are determined by X-ray diffraction. The dielectric properties of the thin films are measured by an Impedance Analyzer. Results show that the Th doped PT films exhibit preferred orientation. The PST thin films deposited on substrate with and without PT inducing layer show (100) orientation and random orientation respectively. Higher (100) orientation appears in the PST thin films deposited on thinner inducing PT layer (one layer compare to more layers). A dielectric tunability of 39% is obtained in the PST thin film deposited on thinner PT inducing layer. It is a little higher than that deposited on thicker inducing layer. (C) 2007 Published by Elsevier B.V.