From the perspective of vegetation density, this research studies the influence of vegetation on turbulence characteristics and Reynolds shear stress in partly vegetated channel via a series of experiments. Natural reed is employed to simulate the emergent vegetation in rivers. Different vegetation densities including vegetated and unvegetated cases are considered in the research. The results of the research demonstrate that emergent vegetation may force the water flowing from vegetated areas to unvegetated areas and the forcing intensity increases with reed density. It is also found that the relative turbulence intensity declines along the vegetated channel in the direction of flow. Vegetation is found to reduce the total-average Reynolds shear stress therefore reduce the soil erosion. However, the Reynolds shear stress reduction is found disproportional to the vegetation density, and an optimal vegetation density range is quantitatively determined in the research. The findings of the research are significant to the practice of river ecological restoration.