In the study of the effects of vegetation on the pollutant transport,PVC cylindrical rods aresimulated as rigid plants and Rhodamine is adopted as tracer substance.The experiments were conductedon a rectangular flume.The result shows that the maximum of concentration of contaminants invertical direction moves to the bottom of the tank with the time goes on.Because of the plants,theflow structure change and the velocity in the plant layer decrease.So contaminants can be detained inthe areas of vegetation.Concentration gradient becomes smaller and smaller with the time goes on andthe distribution of concentration is uniform.Turbulent flow effect will be enhanced under the conditionsof vegetation,increasing the vertical diffusion of pollutants,decreasing the concentration ofdownstream contaminants.So the downstream water pollution is under control.