The invention discloses an electrical equipment appearance abnormity detection method based on image comparison. The electrical equipment appearance abnormity detection method includes normalizing an image photographed during current routing inspection, registering the image with an image photographed at the same position and angle during historical routing inspection, continuing region segmentation on the two registered images respectively, extracting a plurality of characteristics of each region image, fusing the characteristics, calculating difference between the corresponding characteristics of the two images, comparing the difference with a preset threshold value and judging whether the image photographed during current routing inspection is abnormal or not. The electrical equipment appearance abnormity detection method has the advantages that abnormity detection of different types of electrical equipment is achieved under the same algorithm framework; the two images photographed at the same stop and angle by a routing inspection robot during different moments are compared, region changes of the images, with the same content, respectively photographed at a current moment and during historical routing inspection are judged, and accordingly, abnormities, such as damage and foreign-matter suspension, of the electrical equipment are detected.