In this paper, spectroscopic ellipsometry with an incident photon energy range of 2.04.0 eV is used to investigate the optical properties of Mn films deposited on silicon substrates at different sputtering powers. The ellipsometric data are analyzed by Drude and Lorenz oscillators dispersion model. The results show that the refractive index of the film decreases with the increase of the sputtering power. The extinction coefficient of the Mn film increases when the energy of photons is less than 3.0 eV and decreases when the energy of photons is in a range of 3.04.0 eV, and it arrives at an extremum at about 3.0 eV. The extremum shows a red-shift with the sputting power increasing from 60 to 100 W, which is dependent on the quality of the Mn film. With the increase of sputtering power, the extinction coefficient of the film approaches to that of metal manganese. The results also imply that the voids in the film decrease with the increase of the sputtering power, which is conducive to the growth of the films.