Epitaxial MgO thin films were deposited on Si(100) substrate by atmospheric-pressure metalorganic chemical vapor deposition for using as buffer layers. Ba0.6Sr0.4TiO3 thin films were prepared on MgO/Si(100) substrate by sol-gel technique. The independence of crystallinity on annealing temperature was investigated. The Ba0.6Sr0.4TiO3 (BST) thin films are crystallized in preferential (100) orientation after post-deposition annealing at 850°C and 950°C for 2h in air, respectively. Rutherford backscattering spectroscopy analysis confirmed that both the BST and MgO films have stoichiometric composition.