The electro-optic modulation characteristic of the new soft opto-electric materials-ionic liquids was firstly studied by experimental method. It is found that when the modulation signal was low-frequency AC, output optical peak power and AC signal oscillated with the same frequency. Optical power amplitude was found to be dependent on both AC frequency and amplitude. It increased with both the increase of AC amplitude and decrease of AC frequency. When the modulation signal was DC, it could work as an optical switch. The factors which have impact on electro-optic modulation, such as types of ionic liquids, physical size of modulator part, refractive index and electrical conductivity of ionic liquids, were also studied. Preliminarily, a possible explanation was given to the experiments.