Epitaxial Pt films were grown on γ-Al2O3/Si (111) substrate by RF-magnetron sputtering. The γ-Al2O3 buffer layers were grown epitaxially using molecular beam epitaxy. The films were characterized by reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD) and atomic force microscopy (AFM). The results of XRD showed that high-quality Pt films were obtained at around 560°C. In addition, the Pt films exhibited a very smooth surface with the root-mean-square (rms) surface roughness is about 0.4 nm.