[Objective] To uncovered the mechanism of Cynodon dactylon in slope stabilization.[Methods] We tested the spatial variation of plant growth, antierodibility and antiscouribicity with altitude through field investigation and laboratory experiments.[Results] The roots of C. dactylon had significant effects to enhance the soil antierodibility and antiscouribicity. The antierodibility and antiscouribicity of soil-root system increased significantly with the increase of root biomass, which showed linear regression relationship. The antierodibility and antiscouribicity of soil-root system also was influenced significantly by altitude. It increased with the increasd altitude and showed strongest at the altitude of 175 m, the upper edge of the water-level-fluctuation zone.[Conclusion] The C. dactylon community distributing on the upper parts of the water-level-fluctuation zone is submerged slighter and grow better than those distributing on the low parts.