A method for processing dimension numbers using a computing device, a first template of a dimension frame and a plurality of second templates of dimension numbers 0-9, and a numerical text data of each second template are established. A plurality of block objects are obtained by grouping all discontinuous line segments in the engineering drawing. All frame objects in the engineering drawing are obtained by matching each of the block objects with the first template. One or more remainder objects in each bounding box are obtained, and grouped to obtain one or more number objects in each of the frame objects. A matched second template of each of the number objects is obtained by matching each of the number objects with each of the second templates. The number objects in each of the frame objects are replaced by corresponding numerical text data.