Zinc oxide was considered to be substitute for indium tin oxide (ITO) as the transparent conductive oxide (TCO) films used in display industry according to indium is a rare and expensive metal. For the flexible display, the polymeric materials used as the flexible substrates are more bendable and lighter weight compared to the glass substrates used in flat panel display. However, the thermal sensitivity of polymer affects the properties of TCOs layers when it was deposited at room temperature. In this study, we doped the different ratio of indium oxide, magnesium oxide and aluminum oxide into zinc oxide to improve the properties of zinc oxide used as the TCOs films deposited by the sputtering method. The polyethylene terephthalate (PET) was used as the flexible substrate without thermal process and the glass was used as the comparison substrate with annealing. The light transmittance and the surface resistivity were measured. The chemical composition and the crystal structure were analyzed by using Rutherford backscattering spectrometry and X-ray diffraction measurement.