Lithography technology plays an important role in frontier science and national economy and people’s livelihood. With the optimization of optical components such as the exposure light source, digital micromirror device, projection lens and the rapid development of computer control technology, maskless lithography technology based on digital micromirror devices may go hand in hand with the existing well-developed masked lithography technology in the near future, and it will be quite indispensable in certain application fields. In this paper, we introduce the exposure principle, system composition and development history of optical projection lithography based on digital micromirror devices in detail, and we emphasize the strategy for improving the projection lithography resolution as well as achieving ultrafine structures by breaking the optical diffraction limit. Meanwhile, we put forward the unique advantages of projection maskless exposure technology based on digital micromirror devices in achieving micro devices including photonics devices, biological scaffolds and bionic structures, especially its potential applications in novel processing fields by utilizing ultrafast laser.