Indium in oxide(ITO) films have been deposited on PET and glass substrates by DC reactive magnetron sputtering without post-deposition thermal treatment, The high quality for microstructure, electrical and optical properties of the as-deposited ITO films on unheated substrates is dominated by the sputtering parameters, The influence of the working gas pressure, DC power and oxygen partial pressure has been systematically investigated, The lowest DC power, and oxygen partial pressure has been systematically investigated, The lowest resistivity of ITO films deposited on PET substrates was 6$ imes$10$^{-4}$ $Omega$cm. It has been obtained at a working pressure of 3 mTorr and DC power of 30 W. The sheet resistance and optical transmittance of these film were 22 $Omega$/square and 84% respectively. The best values of figures of merit for the electrical and optical characteristics such as T/ $R_{sh}$ and $T^{10}$ / $R_{sh}$ are approximately 38.1 and 7.95($ imes$10$^{-3}$ $Omega$$^{-1}$ ), respectively.