In this work, BST (x=0.7, 0.5, 0.3) films have been deposited onto Nb-SrTiO3 substrate with pulsed laser deposition. The crystal structure and surface morphology have been characterized by X-ray diffraction (XRD) and atomic force microscopy, respectively. XRD results revealed that in certain elaboration condition the films were aligned along (00l) direction, normal to the substrate surface. The dielectric loss, relative dielectric permitivity, and polarization of BST films strongly depended on Sr content at room temperature. The tunability of relative dielectric permitivity of BST films exhibited strongly dependence on Sr content, and BST-0.5 shows the maximun K (K = tunability/loss) value.