Indium tin oxide(ITO)films were prepared on glass substrates at low temperatures by ion beam sputtering.Growth of the films was assisted by He ion beam irradiation. Optical transmission and electrical resistivitywere then measured. In addition, FE-SEM was used to observe the films'microstructure, which was furtherstudied by X-ray diffraction measurements. The relation between beam voltage, transmission rate and electrical resistivity is shown in this study. Finally, theoretical calculation of the Hall mobility and carrier density ITO films by the Van der Pauws method is discussed.