The deposition of indium zinc oxide(IZO) thin films was carried out on glass substrate at room temperature by dc magnetron sputtering. The effects of dc power and deposition pressure were investigated in terms of physical and optical properties of IZO films. As the dc power incerases, the transmittance gradually decreases. For the variation of deposition pressure, the transmittance is decreased with increasing deposition pressure. The observation of IZO films by atomic force microscopy(AFM) indicates that the microstructure and surface morphology of the films are responsible for the transmittance. It was demonstrated that IZO films with an optical transimission of 80 ~ 90% in the visible spectrum could be prepared without post deposition annealing.