The parameters of peak strength are often used to determine the critical slip surface and the length of anchors in schemes of slopes’ reinforcement at present

in fact

the capability of resisting loads and deformation decreases in the slip surface after sliding

there are only residual strength existing. Therefore

a mixed method is proposed to reinforce slopes

that is

the critical slip surface is determined by the parameters of peak strength

while the length of anchors is determined by the parameters of residual strength. The research shows that the safety of the reinforced slopes could be improved by the mixed method.