Transparent and conducting Sb-doped $SnO_2$ thin films were prepared by rf magnetron sputtering technology. But it showed a serious damage phenomenon on the surface of as-deposited films. In order to avoid a damage caused in the substrate center and location facing to target erosion, a ring plate of masking glass was installed at 1.5 cm above target surface. The uniformity and electrical characteristic of $SnO_2$ thin films were evaluated by the control of optimal conditions in the magnetron sputtering operation such as rf power, sputtering gas pressure, and substrate temperature. In the experimental results using the operating conditions, the optimum temperature, which produced uniform and damageless films, shifted with the change of gas pressure. The rate was about $100^{circ}C$/5 mTorr at rf power of 50 W Similarly, the optimum temperature in compensation for an increase of rf power shifted down to a proper rate.