This paper proposes a high sensitive fiber optic microphone based on a micro-electro-mechanical system (MEMS) corrugated diaphragm. The Fabry-Perot interference cavity is obtained with the corrugated diaphragm, which can further improve the sensitivity of the fiber optic microphone. In the theoretical analysis, the finite element analysis software COMSOL is used to model the diaphragm, and the effects of the corrugation width, corrugation depth, and the separation between two corrugations on the sensitivity and working frequencies of the diaphragm are analyzed by simulation. The experimental results show that the sensitivity of the fiber optic microphone based on the MEMS corrugated diaphragm is 630 mV/Pa, and the frequency response range is 50 Hz--8 kHz; and the structure of the fiber optic microphone is simple, which can be well used in the fields of far-field speech recognition and so on.