Abstract: Aiming at tackling the current challenges of limited dynamic range and significant distortion in digital audio reconstruction with speakers, we have developed an electrostatic MEMS (Micro-Electro-Mechanical Systems) speaker with rapid response and linearly summable acoustic output. The speaker incorporates a composite diaphragm structure featuring a dual backplate, cantilever beam, and buffering cone, which significantly reduces the diaphragm's stiffness and enhances its vibrational freedom. Consequently, this design optimizes the operational efficiency and reduces response time. Utilizing Comsol Multiphysics software, we conducted geometrical optimization and performance simulation of the speaker and the optimum combination of structural parameters is determined as follows: the film thickness of the loudspeaker is 1 μm, the film radius is 110 μm, the electrode/film ratio is 40%, and the cavity height is 6 μm. The results confirmed that the acoustic response time of the speaker is under 23 μs, and the acoustic output adheres to the principles of linear superposition, indicating a high-quality acoustic response. These findings suggest that the speaker provides robust technical support for the implementation of digital audio reconstruction. Finally, we have designed a fabrication process for the electrostatic MEMS speaker based on MEMS manufacturing techniques, ensuring the device's precision and performance in real-world applications.