Abstract: Voltage-controlled devices based on tunable dielectric thin film materials are attractive for microwave applications for their excellent high frequency performance, power handling capability, and fast tuning speed. Dielectric voltage-controlled microwave devices offer advantages over semiconductor varactor diodes, ferrite, and MEMS devices with potential integration with microelectronic circuits, small power consumption, low cost, and high reliability. In this paper, based on the recent work of the authors, the recent development of tunable dielectric thin film materials and voltage-controlled microwave devices is introduced. Besides the intensively investigated BaxSr1-xTiO3 (BST) thin films, the alternative tunable Bi1.5MgNb1.5O7 (BMN) thin films with cubic pyrochlore structure are introduced due to relatively high tunability, low loss dielectric loss (~0.002), moderate permittivity (~86), and small temperature coefficient. BMN thin films may be one of potential tunable materials for microwave applications.