Digital Micromirror Device (DMD) is employed as spatial light modulator to construct a digital maskless lithography system,which can be used to fabricate micro-nano photonic device conveniently.The imaging process of the periodic structure in the coherence light is analyzed.According to the numerical simulation and experimental result,the imaging process should be explained by the principle of Abbe′s imaging.With this system,2D periodic structure with the period of 900 nm is fabricated but defect is introduced.So DMD is a practical tool to fabricate submicron-sized pattern.