The invention discloses a binary processing device and method used of image identification. The method comprises steps of according to a preset resolution, carrying out down-sampling operation on a to-be-processed image, and constructing an image pyramid; establishing a corresponding relation between top layer image pixel points and bottom layer image pixel pints of the image pyramid; classifyingthe top layer image pixel points and setting a first target type; according to the corresponding relation between the top layer image pixel points and the bottom layer image pixel pints, marking bottom layer image pixel points corresponding to pixel points of the set first target type in the top layer image pixel points to be second target type so as to obtain a marked to-be-processed image; and carrying out binary processing on the marked to-be-processed image so as to obtain a binary image of the to-be-processed image. According to the invention, a target object can be segmented out from a background in a complete and information maximization manner.