A class of bipolar plate electrostatically actuation microbeam resonator with both clamped ends was studied. The continuum model was established by considering the influences of neutral surface tension and thickness shape error. The thickness shape error was described by a parameter equation with an error parameter, which was used to adjust the degree of shape error. The Galerkin method and NewtonCotes method were used to simplify the system into a singledegreeoffreedom model. The electrostatic force was simulated and verified by the multiphysics finite element software COMSOL. Then, the pullin condition of the system was deduced without thickness shape error. It was found that secondary pullin appears in the system in certain situations. Furthermore, the influence of thickness shape error on pullin condition was analyzed by adjusting the error parameter. The method of multiple scales was applied to obtain the response of smallamplitude vibrations. The influence of thickness shape error on equivalent natural frequencies as well as softening and hardening characteristics of the system were also studied.