Mg-doped (Pb,Sr)TiO3 thin films were prepared on ITO/glass substrate by radio frequency (RF) magnetron sputtering method. X-ray diffraction, ferroelectric analyzer and impedance analyzer were used to analyze the micro structures, ferroelectric properties and dielectric properties of the thin films, respectively. Single perovskite phase solid solution thin films were obtained when the Mg-doping content ranged from 0 to 6 molar percent. Mg2+ substituted Ti4+ in the B-site of the perovskite structure and acted as an acceptor-type dopant to compensate the unbalance of electric charge produced by the intrinsic oxygen vacancies, resulting in the decreased dielectric loss of (Pb,Sr)TiO3 thin films. The variation in tunable properties of PST thin films caused by Mg doping was also studied. (C) 2008 Elsevier B.V. All rights reserved.