In order to realize an accelerometer sensor with high performance, miniaturization anti-electromagnetic interference, long-work hours and long-distance transmission, a novel micro-electro mechanical system (MEMS) fiber-optic accelerometer based on asymmetric torsional mirror is proposed. A dual fiber collimator is used to measure the change of tiny angle of torsional mirror. The MEMS fiber-optic accelerometer consists of asymmetric torsional mirror, drive electrode and dual fiber collimator. The operation principle of the accelerometer and optical detection of the device are analyzed. Basic design and analytical optimization of the device are discussed. The MEMS fiber-optic accelerometer is fabricated successfully by MEMS processes. Measured results of the accelerometer are consistent with the theoretical values. Experimental results indicate that the dynamic range of the accelerometer is ±2g, the bandwidth is 600 Hz and the resolution is smaller than 10-4g. Besides, the accelerometer has good linearity and repeatability. The MEMS fiber-optic accelerometer takes the advantages of fiber-optic measurement, including compact MEMS structure and simple fabrication processes.