Based on analysis of the flow-dividing characteristics and riverbed evolution of the Xiaohuangzhou bifurcated reach of the Yangtze River, the influence of the evolution of the Xiaohuangzhou bifurcated reach on the Xinjizhou bifurcated reach downstream of the Yangtze River was studied using a mathematical model. According to the results, the evolution of the Xiaohuangzhou bifurcated reach has a significant influence on the flow-dividing characteristics of the downstream Xinjizhou bifurcated reach. In the current situation, the recession of the left branch of the Xiaohuangzhou bifurcated reach will lead to the recession of the left branches of the Xinshengzhou and Xinjizhou bifurcated reaches and development of the left branch of the Xinqianzhou reach, while development of the left branch of the Xiaohuangzhou bifurcated reach will lead to development of the left branches of the Xinshengzhou and Xinjizhou bifurcated reaches and a small change in the left branch of the Xinqianzhou bifurcated reach.