It has been considered that applying symmetric addressing schemes can avoid the ionic effect in FLCDs. In this paper, image sticking measurements have been performed to investigate the ion transport process on applying symmetric addressing signals and hence its influence. It has been found that by reversing the polarity of the addressing voltage each frame, image sticking effect has been prominently reduced, nevertheless not completely to zero. Further study has revealed the fact that although accumulation of ions is avoided to a large extent, a number of ions are still trapped at the interface of alignment layer and the liquid crystal layer. These trapped ions cannot be easily released by simply reversing the polarity of the addressing signal and thus influence the electric field distribution in FLC. The number of trapped ions depends on the property of the interface.