为了研究长江中下游分汊河道的稳定性，在总结其 演变特点的基础上，分析了分汊河道赖以长期稳定的原因，并用河床自动调整理论和能耗最小假说来加以解释。认为特定的来水来沙条件和汊道进出口节点的控制作用，使得分汊河道 的能量分配可以通过向支汊输送一定流量来实现。

In order to study the stability of branch channels o f Yangtze River's middle and lower reaches ,on the base of summarizing the evolu tion features of branch channels,the causes of longterm stability of branch ch annels are analyzed and explained by using automatic adjustment theory of riverb ed and energy loss minimum hypotheses.It is considered in this article that spec ific watersand conditions and control function of branch channel's import and export nodes make energy distribution to be achieved by transporting a specified discharge to branch.