The effects of sputtering conditions on the transport properties of YBa 2Cu 3O y (YBCO) thin films were investigated in this work using an off-axis RF sputtering configuration. These conditions included the substrate temperature, the distance from the substrate to the target, the total pressure of the sputtering gas and the gas composition. The substrates were MgO (001) and SrTiO 3 (001) and the sputtering gas was a mixture of Ar and O 2. The YBCO films were characterized by resistivity measurements, X-ray diffraction and scanning force microscopy (SFM). Additionally, the optimum conditions of growing high-quality YBCO films were obtained. Those conditions were found to be: (1) the substrate is 3.5 cm horizontal and 3.0 cm vertical away from center of target, (2) the substrate temperature is 680°C for MgO and it is 720°C for SrTiO 3, and (3) the pressure of the sputtering gas of Ar : O 2 is (3 : 7) at 300 mTorr. The high-quality YBCO films revealed a transition temperature T c( R = 0) at 87 ∼ 90 K, a normal-state resistance ratio R 300K/ R 100K ∼ 3 and a normal-state resistivity at 300 K smaller than 200 μΩ cm.