Abstract: Since the 1970s, especially since the mid-1980s,the bank full wid th of channel of the Yellow River became smaller, the width to depth ratio became lower. Results indicate that the channel at the lower Yellow River is affected by both reservoir operation and oncoming flow and sediment. Finally, a well-deve loped mathematical model is used to estimate the possible trend of the channel pattern under the Xiaolangdi reservoir operations and oncoming flow series.