The invention discloses an image enhancing method based on self-adaptive block channel stretching. The method mainly solves two important problems of image defogging and exposure adjustment in image enhancement. In the prior art, many methods provide solution schemes for the two problems, but the methods have the defect that a plurality of thresholds for image adjustment are needed, and this kind of methods requires user interaction operation and fail to process a plurality of images at one time; in addition, in the prior art, fogged images and dark light images are taken as two kinds of image enhancing problems which are solved respectively, and a unified framework is lacked. Aimed at the defects of the existing methods, statistic learning is carried out on various kinds of images in a real world, a self-adaptive threshold of problem image adjustment is obtained, the manual interaction operation of a user is reduced, and the processing efficiency is improved; in addition, stretching conversion is simultaneously carried out on a highlight channel and a shadow channel of an image block, and the problem images including the fogged images and the dark light images can be enhanced under the same framework.