The micro-scale lateral deformation behavior of ionic polymer-metal composite （IPMC） cantilever actuators under alternating current （AC） excitations is investigated by experimental method in the paper. A digital microscope system is used to record the micro-scale lateral deformation process of IPMC cantilever structure under AC excitations， and the digital image correlation （DIC） method is utilized to analyze displacement and strain responses of the sample. The results indicate that oscillation center of IPMC sample occurs offset vibration， and the frequencies of offset vibration are much lower than those of the excitations. The vibration amplitude of IPMC sample increases linearly with the increase of excitation voltage， and decreases exponentially with the increase of excitation frequency. The longitudinal normal strain is linearly distributed along the thickness direction， which increases （decreases） linearly with the increase of excitation voltage （frequency）