From the 1960s, the evolution of channel morphology and river state in the lower Yellow River has been studied to different degrees with mapping methods and aerial photos by academic circles of geomorphology. With increasing accumulation of research materials, this study has been gradually deepening. During “the Eighth Five Year Plan”, a further analysis of mainstream line in the lower Yellow River has been carried out by hydrological circles and the results indicated that this status must be further analyzed and discussed because of different conclusions. In our study, the following conclusions are drawn: Firstly, the asymmetrical channel morphology in the lower Yellow River is a geological evolutionary process and a kind of synthesized result influenced by such factors as tilting down from north to south caused by neotectonic movement inheriting from old structural movement, coriolis force, recent human activities and geomorphological factor. Recent human activities including construction of the Xiaolangdi reservoir will not change the asymmetrical pattern of the channel in the lower Yellow River, but facilitate further development of asymmetrical channel morphology. Secondly, a kind of deflective resultant force southward caused by impact of asymmetrical channel in the lower Yellow River on the water body leads to continually stronger erosion to the southern bank of the river than to the northern. Thus, the tendency of southward shifting and meandering of the mainstream line will not change. The same is true of the Xiaolangdi reservoir after the completion of the project. Thirdly, according to empirical analysis of the Sanmenxia reservoir, there is an indication that although the wandering intensification of the channel was influenced by reservoir to some extent, the channel pattern didn’t change completely. It is expected that construction of the Xiaolangdi reservoir will not change the channel pattern in the lower Yellow River. Lastly, although construction works for harnessing the lower Yellow River channel can control meandering range and weakening wandering intensification of the channel, they cannot change the evolutionary tendency of channel morphology above mentioned ultimately.