The electrostatic field distribution of interdigital electrode (IDE) piezoceramics and piezoelectric fiber composite were analyzed by finite element method separately. The impact of the interdigital electrode asymmetry on the actuation performance of piezoelectric actuators with a certain interlayer thickness was studied. The influence of the interdigital electrode asymmetry on the actuation performance, stress concentration and electrostatic field concentration with different interlayer thicknesses were also discussed and compared. For piezoceramics, the results showed that the actuation performance could be influenced little by increasing the degree of the excursion with a relatively thin interlayer thickness. As the interlayer thickness increased, the actuation performance could be influenced much by increasing the degree of the asymmetry. And it resulted in the decrease of the longitudinal free strain overall. Regardless of how the thickness of the piezoelectric material changed, the electric field became increasingly uneven as the degree of the asymmetry increased. The actuated stress could be improved evidently by increasing the degree of the asymmetry with a relatively thin interlayer thickness while the stress concentration was not increased apparently. For PFCs, the thicker the thickness between the electrode and the fiber, the greater the actuation performance would be influenced by the asymmetry.