Abstract: The present disclosure provides an apparatus and method for wavefront reconstruction based on rotationally symmetric extended structured light illumination. The apparatus includes a laser device, a neutral density filter, a microscope objective, a pinhole, a collimating lens, a beam splitter prism, a spatial light modulator, a lens to be measured, and an image acquisition device that are sequentially arranged. The method permits modulation of incident parallel light into phase grating-like structured light by using a spatial light modulator. Based on the characteristic of non-infinitely small pixel unit of the spatial light modulator, changing the modulation pattern of the spatial light modulator may result in different forms of structured light.