CTO (Cadmium Stannate) thin films, one of TCOs (Transparent Conducting Oxide) having a potential application for photovoltaic or display product, were prepared by using rf magnetron sputtering system. The lowest resistivity of CTO thin film deposited at room temperature was 6.6 x 10(-4) ohm.cm with carrier mobility of 9.1 cm(2)/Vs and carrier concentration of 10.4 x 10(20) cm(-3). The average transmittance of CTO thin film was found to be over 80% regardless of deposition condition. The transmittance of the annealed CTO thin film at 600 degrees C in air atmosphere, was found to increase upto more than 90%, but the film resistivity degraded by two order of magnitude due to the decreased carrier concentration with minor increase of carrier mobility.