Abstract: HfO2 thin films were deposited on single crystalline silicon substrate by using magnetron sputtering in totally reactive oxygen plasma. Effect of substrate temperatures on the structure and properties of HfO2 films were investigated. Phase structure, component and surface topography were characterized by using the Xray diffraction analysis (XRD), Xray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM), respectively. The mechanical properties of the films were measured by using the nanoindentation. It is indicated that the (111)oriented HfO2 films could be obtained and the structure of the asdeposited films was not changed as the increase of the substrate temperature. The stoichiometric ratio, surface topography and nanomechanical properties of the asdeposited films were dependent on the substrate temperature. The stoichiometric ratio would be deteriorated with the substrate temperature increasing, which was attributed to the diffusion of silicon. The best substrate temperature was found to be 200 ℃. The atom ratio of O/Hf for the asdeposited films could arrive to be 1.99. In addition, the lowest value of rootmeansquare(RMS) roughness and the maximum value of hardness and elastic modulus were obtained.