The electromechanical properties of an electro-active artificial muscle of poly(styrene-altmaleimide)/poly(vinylidene fluoride) with glycerol as a solvent at ultralow frequencies were investigated. Actuated at higher potentials and in the open air, the artificial muscle showed no back-relaxation, and the deformation increased steadily as long as the voltage was applied quasi-statically. Under a simple stimulus with such low frequency as 0.005Hz, the artificial muscle displayed excellent harmonic responses, and its actuation performance was observed to be improved continuously by a self-activating process along with the time increased. This is attributed to a combination effect resulting from the unique nanochannels of the ionic network polymer and the large inertia mass of the viscous glycerol.