In order to study influences of force attenuation and cable failure of prestressed anchor on the stability of the right guide wall, taking the actual situation of a project as an example, the ANSYS finite element software was used to simulate the spillway right guide wall and to validate the scheme feasibility of the given anchor reinforcement, also to study impacts of the constant decrease of prestressed anchor cable and the failure of single row anchor on the structure stability of the right guide wall. The results showed that the given anchor cable reinforcement scheme is feasible. The structure stability of the right guide wall continues to decrease with the attenuation of the prestressed anchor cable, the structure stability of the right guide wall reaches ultimate bearing state when the prestressed anchor cable attenuation decreased from 3000kN to 500kN, the top anchor rope failure has the greatest effect on the structure stability of the right guide wall.