Abstract: The natural slope failures are often found after constructing mountain road due to cutting their foots. Taking the cut slope in Daganping as example, the Daganping clay was tested under the unloading stress-path on triaxial equipment forits, in order to quantify the parameters for stability analysis of the slope. A non-linear FEM for analysis of stability of the cut slope is established. The results provide a clear description of the extension of plastic zone in the slope during cutting and bracing. The location of slip surface is determined from the results by FEM. The variation of ground water table in the slope are monitored in field during seepage. The limit equilibrium method is used to calculate the safety factor of slope stability, and the stability is estimated from calculation results. According to the FEM results, the methods of slope treatment including a bracing system with retaining wall and a drainage system with a bunch of tree branches are presented. The observation shows that the result of the treatment is satisfactory in practice.