Based on micro-electromechanical systems (MEMS) technology, a new MEMS Fabry-Perot filter structure combining with grating and Fabry-Perot cavity is proposed. This filter can not only ensure a wide free spectral range, but a narrow full width at half maximum (FWHM). The implementation mechanism, the parameters selection and the structure of the Fabry-Perot filter are analyzed deeply, and a simulation to calculate the mechanical and electrical properties of the micro-bridge deck is made. By choosing different thicknesses of the micro-bridge deck (0.5, 0.6, 0.7, 0.8, 0.9, 1 μm), and comparing with the flatness of micro-bridge within electrostatic interactions, it is found that when thickness is 1 μm and voltage is 5 V, the tilt displacement of the upper-mirror is 9.11 nm and the maximum cavity length change is 242 nm, which can maintain top and bottom cavity surface reflecting light parallel, and ensure filter′s filtering efficiency and selected light utilization. This novel filter is able to solve the contradiction that the free spectral range and the FWHM restrict from each other in traditional micro-filters. Thereby, the performance of the micro-filter has improved.