As a common type of river，the flow characteristics of branching channel are of great significance in river bed evolution and channel maintenance. We take the branching channel as the research object，apply the physical model test of natural beach generalization，obtain the flow law of branching channel. The results show that there are low velocity zones in front and back of the beach，and the velocity distributions of the two branches are asymmetrical. The maximum velocities of two branches appear alternately. The variation of velocity along the river is consistent with the trend of beach elevation，and the maximum velocity appears at the highest point of the beach（under the condition of total flooding）. The diversion ratio decreases with the decrease of the branch width. When the beach is near the center of the channel，the diversion ratios of the two branches are equivalent. When the beach is near the shore，the diversion ratio of the narrower branch becomes smaller，but the velocity changes greatly，and the flow is more unstable.