In this paper the ultraviolet—visible photoabsorption spectrum of the complex thin films of noble metal (Au,Cu) particles embedded in BaO matrix is measured.The absorption spectra of the two kinds of films are quite different.There are surface plasmon mode and band transition absorption in the spectrum of the Au-BaO thin film.However,several peaks appear in the spectrum of the Cu-BaO thin film,because Cu exists as very small particles in the matrix.The absorption spectrum is dependent on the metal content.