BaTiO3 thin film with average size of 50 nm was prepared on crystalline silicon substrate by r.f.-magnetron sputtering. X-ray diffraction indicated that the thin film was tetragonal phase with (c/a) = 1.0068. Variable-temperature Raman spectroscopy showed the thin-film Curie temperature increased evidently, relative to BaTiO3 ceramics, by the observation of tetragonal bands at 305 and 720 cm(-1) which were retained even at 275 degrees C. The stress in the thin film was measured to investigate the mechanism of the stabilization of tetragonal BaTiO3.