In this paper, a novel redesign of the prestress mechanism of the stack-type piezoelectric ceramic actuator is provided. Belleville (disc) springs which have a specific height-to-thickness ratio are constructed to generate a constant pre-stress force to the PZT and operated in a special condition. The prestress mechanism is not only used to against the tensile stress but also used to improve the output performance of the actuator. The simulation of the structural behavior is constructed and analyzed in ATILA program by modifying the related parameters of the piezoelectric and the elastic materials, the modal and harmonic analysis are both established in the FEA model. The feasibility of the pre-stress experiment is determined by the simulation result subsequently in this paper. The comparison of the output force and the natural frequency of the pretress mechanism between the different settings of the actuator designed in this study and the commercial products reveal that the linearity of the output force can be maintain and the new prestress mechanism exhibits an extremely low natural frequency which approach to zero as height-to-thickness ratio of the Belleville springs equal to √2. It means our new mechanical concept of the actuator can effectively promote the output efficiency which preserves the output force linearity of the piezoelectric ceramic; the excitation of the PZT or external vibration cannot establish the resonant frequency condition due to the improved design of the prestress mechanism.