Scanning Dammann lithography (SDL) is proposed and implemented, which uses a Dammann grating to generate multiple beams with sharp step boundary for writing large-sized gratings efficiently. One of the most attractive advantages is that this technique can accelerate the writing speed, e.g. 1 \times 32 Dammann grating can be 32 times faster than the single laser scanning system. More importantly, the uniformity of the multi-beams-written lines is much better than the single laser beam scanning system in consideration of the environmental effects such as air turbulence, thermal instability, etc. Using the SDL system, a three-port high-efficiency beam splitter at visible wavelengths is fabricated quickly, and the theoretical and experimental diffraction efficiencies are both higher than 90%. Therefore, SDL should be a useful tool for fabrication of large-sized gratings.