Nonepitaxially grown Ba0.6Sr0.4TiO3 (NE-BSTO) thin film with tunability of 65.4% and low leakage current was obtained on Ir electrode by oxygen plasma-assisted pulsed laser deposition (PLD), and epitaxially grown Ba0.6Sr0.4TiO3 (E-BSTO) thin film with tunability of 32.5% was obtained by PLD without plasma assistance. Results indicate that the NE-BSTO film possessed higher oxygen content, lower tetragonal distortion, and low stress, all of which contributed to its excellent dielectric properties. This work demonstrates that NE-BSTO thin films are well suited for room temperature tunable microwave device applications.