Abstract: According to the transmission and reflection spectra in the visible and near IR regions of the transparent conductive cadmium indium oxidate thin film deposited by RF reactive sputtering from Cd In alloy target,the optical constants of film is determined by using the iterative method on the envelope line and the model about the optically inhomogeneous film presented by Szcyrbowski J, respectively.The effective mass of the free carrier can be calculated on the basis of classical Drude theory,and compared to that determined from the plasma wavelength λ_p.