Ferroelectric thin films are a kind of functional ceramic films which can be used as nonvolatile memories.Recently,the resistive switching effect in ferroelectric thin films induced by polarization reversal have been studied extensively because it is possible to achieve great data storage performance with high reliability,high resistive ON/OFF ratio,high speed,high reproducibility and low write power.However,great resistive switching memories effect is mainly found in high-quality epitaxial ferroelectric thin films,while few in polycrystalline thin films due to the existence of the grain boundary defects.