The invention discloses an illumination-classification-based adaptive image segmentation method which is used for accurately segmenting a target object under different illumination conditions. The illumination conditions are divided into two types, namely a frontlighting type and a backlighting type, by extracting color characteristics of an image to be processed in a red, green and blue (RGB) space and a hue, saturation and value (HSV) space and adopting a minimum euclidean distance classifier; a proper color characteristic quantity serving as a segmenting parameter is extracted from the image in the two illumination types and imported into a two-dimensional histogram; neighbor information of each pixel point is increased, so the interference resistance capacity is improved; and the acquired image is subjected to intelligent illumination judgment and precise segmentation. In the illumination-classification-based adaptive image segmentation method, a mode of judging the illumination condition first and then selecting a segmenting algorithm is adopted, so the algorithm has higher pertinence and the effectiveness of the algorithm is improved; meanwhile, illumination correction is not required, so the computing cost is reduced greatly; and a favorable condition is created for the subsequent image processing and analysis.