Indium tin oxide (ITO) thin films are deposited on glass substrates at 190 ℃ by direct current (DC) magnetron method. The photoluminescence properties of ITO thin films are investigated by using fluorescence spectrophotometer. With the photon excitation wavelength of 250 nm at room temperature, ITO films show a strong broad blue emission and a weak red emission centered at around 467 and 751 nm, respectively. The blue and red emissions of ITO films are related with the energy level formed by oxygen vacancies and indium vacancies in forbidden band. Oxygen vacancies results in a donor energy level at 1.2 eV below the bottom of the conduction band. Meanwhile, an acceptor energy level resulted by indium vacancies at 1.65 eV above the top of the valence band is observed.