PZT thin films (3500$AA$) have been prepard on the Ru/Ru $O_2$ and Ru $O_2$ bottom electrodes with a RF magnetron sputtering system using P $b_{1.05}$(Z $r_{0.52}$, $Ti_{0.48}$) $O_3$ ceramic target. Ru/Ru $O_2$ bottom electrode was fabricated by in-situ processing controlled the $O_2$ partial pressure. The PZT thin films deposited on the Ru/Ru $O_2$ bottom electrode were preferred oriented (101) plane. The PZT thin films deposited on the Ru/Ru $O_2$ bottom electrodes showed better electrical properties than those with Ru $O_2$ bottom electrodes because Ru $O_2$ prevented oxygen vacancies and impurities from existing withing the interface and substrate.e.