The BMN/BST multilayer and BMN-BST composite thin films have been fabricated by pulsed laser deposition on Au/TiOx/SiO2/Si substrate. The multilayer thin films comprising one, two, and four periodic compositional Bi1.5MgNb1.5O7/Ba0.6Sr0.4TiO3 (BMN/BST) layers (PCBLs) have been elaborated with the final same thickness. The four PCBLs show the largest dielectric constant of similar to 168 and tunability of 40.6% at a maximum applied bias field of 0.67MV/cm and the lowest loss tangent of similar to 0.006, whereas the figure of merit (FOM) is 72. The BMN-BST composite thin films exhibit medium dielectric constant of similar to 238, low loss tangent of similar to 0.0053, and superior tunable dielectric properties at room temperature. Calculations of tunability and FOM display a maximum value of 49.3% at 670kV/cm and similar to 88, respectively.