An apparatus for detecting an array substrate comprises: a transparent carrier for supporting an array substrate to be detected thereon; a light source disposed on one side of the transparent carrier; and a modulator disposed on the other side in parallel with the transparent carrier. The modulator comprises a liquid crystal layer and two transparent substrate layers disposed on both sides of the liquid crystal layer, and one transparent substrate layer away from the transparent carrier is a first transparent conductive substrate layer, and a second polarizer is disposed thereon. A first polarizer is disposed between the light source and the transparent carrier, so that the light emitted from the light source is transmitted through the first polarizer to the transparent carrier. A light receiver receives the light emitted from the light source and then transmitted through the transparent carrier, the array substrate and the modulator.