River channel geomorphologic evolution is the basis of flood control and regulation. With the information of satellite images and field investigation, the article emphatically analyzes the geomorphologic evolution characteristics and stability of meandering channels and gooseneck-bifurcated channel, both of which are the most typical and unstable types in the middle and lower Yangtze River. Evolution of meandering channels has characteristics of periodicity and length constraint. The fractal dimension of Lower-Jingjiang is between 1.078 and 1.23. When it reaches a value between 1.19 and 1.23, river channel goes to an unstable status, in that case the fractal dimension will have mutation from big to small, because of the channel cutoff. Stone serving as node, heart-shape beach, branch inflow are the main conditions of the forming of gooseneck-bending channel. Most gooseneck-bifurcated channel has the characteristics of periodicity integer nested translation. Recently most of the left branches are at the stage of bankrupt-siltation-bank combined Lower-Jingjiang meandering channel has the characteristics of variability at the transverse direction and linkage at the vertical direction, so river regulation should be based on the whole part of the river. Bifurcated channel below Chenglingji should be governed from different units according to the node. More branches, more unstable the channel will become, besides, the branch also has the characteristics of linkage, and so all branches should be treated as an entirety when having the river regulation.