Abstract: A model concerning the evolution of small vegetative patches for generalized river was established to study the succession of vegetation. Two-dimensional shallow water equations were taken as the governing equations, which was solved by the finite volume method. The equivalent Manning coefficient was applied to generalize the effects of vegetative patches. New vegetation would emerge in regions where the bed shear force is lower than the threshold and disappear on the contrary. The influence of vegetation drag on flow and bed shear force on vegetation succession was considered. A mathematical model coupling the growth-decay of vegetation and hydrodynamic process was then established to simulate the succession of vegetation under different conditions. Two thresholds of bed shear force and two initial densities of vegetative patches were focused during the simulation. The results show that the vegetative patches in river usually evolve from block-shaped to strip-shaped, and a higher threshold of shear force is always related to a larger final area of vegetation. The final vegetation area accounts for 47%~49% of the total river area when the threshold coefficient of shear force is 0.5. However, the ratio comes to 58%~60% when the threshold coefficient is 0.7. Different initial vegetation distributions have no influence on the final vegetation coverage, but larger initial vegetation density can produce more rapid initial growth, causing the vegetation area to reach a basically stable state more quickly.