Au/SiO2 nano-composite multilayer thin films were prepared by magnetr on plasma sputtering. The microstructure, morphology and optical properties were investigated using transmission electron microscopy and absorption spectra. The Au particles dispersed in the SiO2 matrix of one single Au layer gre w with increasing deposition time in the initial time interval of less than 10s. No obvious change in the size of Au particles was observed in the films deposit ed for more than 10s, however, the shape of Au particles changed. The optical ab sorption peaks due to the surface plasma resonance appeared at a wavelength of 5 40—560nm for ［Au(t1)SiO2(600)］×5 thin films . The intensity of the absorption peak increased with increasing deposition time . Influence of the Au particle shape on the position and intensity of plasma res onance absorption peak was also discussed. The optical absorption spectra of Au/ SiO2 thin films are well in agreement with the theoretical optical ab sorption spectra calculated from reformed Maxwell-Garnett effective medium theor y.