Abstract: The present disclosure provides a mask plate, an exposure device and an exposure method. The mask plate includes a base plate and a plurality of patterns with openings arranged on the base plate. The base plate includes a first region corresponding to a position where a developing agent has a low concentration in the case that a target substrate is to be developed, and a second region corresponding to a position where the developing agent has a high concentration in the case that the target substrate is to be developed. In the case that the target substrate is exposed using the mask plate, an amount of light beams passing through each pattern at the first region of the base plate is greater than an amount of the light beams passing through each pattern at the second region of the base plate.