Abstract: MEMS(micro-electro-mechanical system) is a new fabricating technique, Which is widely used in the optical communication and has a great value in the communication market.The optical switch is an important passive device,which can selectively control optical signals in the optical communication of optical network system. The new type of optical switch, which is made with MEMS, has many advantages, such as small size, light weight, low consumption and high integralization. Therefore, the research on the optical switch has become an object which more and more experts are hunting for. In this paper, the MEMS and its main characteristics are briefly introduced, the application of MEMS in the optical communication thoroughly described, and the structure, the trend of development and the main problems of the MEMS optical switch are analyzed respectively.