Abstract: Based on the results from a series of simple shear tests for simulation a reinforced cut -- off slope with steelbars, this paper proposes a calculation method to evaluate the shear resistance and effect of the reinforcing materialsinvoking the theory of the lateral resistance of foundation pile. It is shown by the comparison between data obtainedfrom calculation and tests that the calculation method is highly effective until large shearing displacements appear.The role of both tensil force and shear force in reinforcing materials is also discussed based on the results ofcalculation and tests.