Gold–silver (Au–Ag) bimetal dispersed SiO2 composite films were fabricated via a chemical solution approach combining sol–gel with a spin-coating process, and they were investigated by transmission electron microscopy (TEM), x-ray photoelectron spectroscopy (XPS), and ultraviolet-visible absorption spectra. TEM image indicated that Ag and/or Au nanoparticles (NPs) had a spherical structure with large size distributions. The XPS results demonstrated that the presence of both Ag and Au NPs in the composite film is in each metal state. The optical absorption spectra of the composite film further confirmed the formation of nanosized Au and Ag particles, given by the two surface plasmon resonance (SPR) peaks. Unlike other Au–Ag composite films, these two SPR peaks had almost the same intensity, which is rarely obtained by a chemical approach. Compared to optical absorption spectra calculated by the modified Mie theory, the location and intensity of SPR peaks had a little difference, which could be attributed to large size distributions of Ag and Au bimetal NPs in the composite film along with the experimental process. In addition, the intensity of both SPR peaks was content-related.