To improve the reliability of micro-electro-mechanical system (MEMS) micromirrors during their operation, an electromagnetically driven MEMS micromirror with a mirror measuring 5 mm×6 mm and a new torsion beam structure is designed. A finite-element simulation algorithm is used to simulate the MEMS micromirror, improve the design rationality of its motion mode, and complete the process preparation and encapsulation of the designed structure. The prepared two-dimensional MEMS micromirror offers the advantages of simple process, low manufacturing cost, and high corner stability. Test results show that the MEMS micromirror equipped with the new torsion beam can achieve biaxial rotation, with a fast-axis resonant frequency of 1082.2 Hz and an optical angle of 53.9°, as well as a slow-axis operating frequency of 60.0 Hz and an optical angle of 20.8°. The results of stability test indicate that its mechanical half-angle error is 0.21° and its overall angle fluctuation is less than 2.6%. This two-dimensional MEMS micromirror has a large angle and exhibits high stability, thus satisfying the demands of MEMS lidar.