Abstract: Fast steering mirrors(FSM) are an essential component of optoelectronic precision tracking systems and are widely used in consumer electronics, medical, astronomical telescopes and laser communications. The fabrication of a micro-electromechanical system (MEMS) based on silicon is important for the miniaturization and lightweighting of the mirror and tracking system. This paper presents the structural design, process selection and fabrication process of a silicon-based mirror. Through a comprehensive analysis of processing convenience, processing accuracy, processing reliability and fabrication cost. Technical ideas of a movable structure for miniaturised fast-reflector by MEMS deep silicon etching process is determined. In the fabrication of the mirror, the problem of uneven deep silicon etching was solved by reducing the etched area through the “surface to line” layout optimization, the problem of surface cleanliness of the mirror was solved through the comparison and selection of cleaning methods, and the problem of surface shape accuracy control of the mirror was solved by changing the metallization method. The test results show that this miniaturised fast reflective mirror based on the silicon-based MEMS process meets the requirements of the design and application.