In this paper, a new method of image enhancement, which only depends on the difference of grey values of adjacency flat zones of an image, is proposed according to the theory of morphological reconstruction. First of all, a non-idempotent connected operator which can be the criterion for multi-scale enhancement is defined and the criterion is a key to enhancement of an image. Subsequently, the grey values in same the simple connected zones of an image are enhanced overall so the way can keep the immovability of the image contour. At last the connected zones of an image and their relations are described and the way of the multi-scale morphological reconstruction enhancement for an image is implemented by using maximum tree or minimum tree structure. Lots of experimental results indicate that this method can not only stretch the contrast according to the character of gray level of connected zones of an image, but also protect the relations of gray level of connected zones. It’s an effective enhancement method of an image.