The invention provides a mask plate detector, a mask plate detecting method and mask plate washing equipment. The mask plate detector comprises a detecting module and a control module, wherein the detecting module is used for detecting residues on a mask plate and generating detection information; the control module is used for determining the detection result based on the detection information; the detection result is used for identifying the cleanliness of the mask plate. With application of the mask plate detector, the cleanliness of the mask plate can be detected automatically, so as to increase the detecting efficiency, accuracy and safety of the cleaning effect of the mask plate.