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