The Mangdantan channel,consisting of three continuous branches,locates in the middle and lower reaches of the Nujiang River with bad flow condition.To investigate the natural navigation obstruction characteristics in Mangdantan continuous branching channel,the influence of different discharges in normal and dry period on the flow diversion,gradient,water depth condition and current speed distribution are numerically analyzed by the two-dimensional planar hydrodynamic model.The results show that the natural navigation obstruction characteristics include large gradient,insufficient water depth and rapid current speed.In addition,the flow condition in the branches R1-L2-L3 is better than those in the branches R1-R2-L3,therefore the branches R1-L2-L3 are suggested to be developed as the navigation channel.The research results can provide technical support and theoretical guidance for the regulation of Mangdantan and the channel development of similar continuous branching rivers.