Deformable mirror (DM) is a very important element in adaptive optical system,and it can perform dynamic phase modulation and endow optical system the ability to decrease the influence of dynamic wavefront errors. Deformable mirror of conventional adaptive optics can not satisfy the need of miniaturization and integration,but the deformable micro-mirror based on microelectro-mechanical systems (MEMS) can solve these problems. The theory and development of MEMS-DM and its application in adaptive optics are summarized,the fitting capability of MEMS-DM are discussed. At last,a prospect of MEMS-DM is given.