Abstract: Hinge jointed concrete facing system is extensively used in bank protection engineering because of its good applicability to small-scale deformation and its high strength, intense compactness and strong shock resistance. Vetiveria zizanioides with strong deep roots have better anchoring force and shear resistance. Vetiveria zizanioides grow in ringent hinge jointed concrete extending system, and its roots are interlaced and make foundation soil into compound materials of soil and roots, but grass roots are considered as three-dimensional reinforced materials which increase soil strength and the stability of bank protection. Based on the theory of slice method, the mechanism of reinforcement with roots is analyzed.