This study investigates the development of lower channels and sediment sorting processes in the vegetated channels with the mixed sediment. The sediment discharges fluctuate with time and decrease with vegetation density. The bed changes with irregular patterns, and the sediment particles in the vegetated zone at the surface of bed are fine. The dimensionless geometric mean decreases with vegetation density. The fine sediment particles are trapped by vegetation, and the bed between main steam and vegetated zone increases. Moreover, the particle sizes are distributed irregularly near the zone. The hiding functions decrease with dimensionless particle size. However, the functions increase with vegetation density, which is confirmed by decreasing sediment discharge with vegetation. The lower channel is stable and the migration decreases in the condition of 0.5 . However, the migration of the lower channel in the condition of 0.7 increases due to the increased sinuosity and new generated channels in the sedimentated vegetation zone.