Abstract: The present application discloses an ultra-micro defect detection apparatus and a detection method thereof. The apparatus includes an imaging module, a light source module, a filtering module, and a mounting platform; the imaging module further includes a camera, an imaging lens, and an objective lens; the camera, the imaging lens, and the objective lens are sequentially and vertically arranged from top to bottom; the light source module further includes a collimator, a light source generator, and a beam splitting mirror; the light source generator is connected to the beam splitting mirror, and the collimator is mounted between the light source generator and the beam splitting mirror; the filtering module further includes a spatial filter, and the spatial filter is mounted between the imaging lens and the objective lens.