Ag2O film has a potential application in high-density optical and magneto-optical disks. In this paper, a series of Ag2O films is deposited by radio-frequency reactive magnetron sputtering at different substrate temperatures, a deposition pressure of 0.2 Pa and an oxygen flow ratio of 2:3. The spectroscopic ellipsometry spectra of the films are fitted by using a general oscillator model (including one Tauc-Lorentz oscillator and two Lorentz oscillators). In an energy range between 1.5 eV and 3.5 eV, the refractive index and extinctive coefficient of the film are in ranges between 2.2 and 2.7, and between 0.3 and 0.9, respectively. The film indicates a clear abnormal dispersion in an energy range of 3.5 eV and 4.5 eV, meaning that the plasma oscillator frequency of the film is in this energy range . A redshift of the absorption edge of the film occurs with substrate temperature increasing, which can be attributed to the increased lattice strain. The optical constants of the film clearly show the dielectric properties.