Abstract: This paper presents the results of high-temperature X-ray diffraction (XRD) study and temperature dependency analysis of the dielectric of BaTiO3(Ni) thin film on the SrTiO3 substrate. The results show that the phase transition temperature of a BaTiO3(Ni) thin film has a wide range. The tetragonal to cubic phase transition of BaTiO3(Ni) thin film was reversible, but the reversible phase transition didnt occur immediately after cooling process. The dielectric dispersion of BaTiO3(Ni)/SrTiO3 was caused by the stress and the mismatch between BaTiO3 thin film and the SrTiO3 substrate, and the effect of Ni nanocrystals. The dielectric relaxation was deviation from the Deby relaxation, and the dielectric loss increased with the increase of temperature. The results from the Cole-Cole plot show that the tetragonal to cubic phase transition of BaTiO3(Ni) thin film included several polarization mechanisms function. The dielectric loss increased with the increase of temperature at a high temperature. The film was not restored tetragonal phase immediately in the cooling process, which might be the combined effect of both substrate and Ni particles.