The present disclosure provides an automatic exposure control method, including: providing an object to be tested; providing an image sensor, including a photosensitive element array composed of a plurality of photosensitive elements arranged in an array, and the photosensitive element array includes at least a plurality of first photosensitive elements and a plurality of second photosensitive elements; turning on the radiation source, and the first readout signals on the first photosensitive elements are read after exposing the area to be tested for the first preset time; continuing the exposure for the second preset time, turning off the photosensitive elements and reading the second readout signals on the second photosensitive elements; acquiring the preset dose threshold of the area to be tested based on the second and first readout signals, and obtaining the remaining time to reach the preset radiation dose to control the exposure of the radiation source.