To fabricate plain holographic gratings with high wavefront quality and to obtain the wavefront required in varied line-space grating, an active control technology of a diffraction grating wavefront by modulating the phase distribution of the scanning-beam interference lithography system was proposed. Sinusoidal wavefront control is simulated, and the controlled wavefront being almost the same as the target wavefront. A photoresist grating was fabricated whose surface is uniform and the wavefront is ideally sinusoidal. The theoretical analysis and experimental results confirmed that the wavefront of the diffraction grating can be actively controlled by modulating the phase distribution of the scanning-beam interference lithography system.