Abstract：The factor of safety of a slope based on limit equilibrium method is largely dependent upon the assumption regarding the distribution of normal stresses on the slip surface. Thus，investigation of the effect of this distribution on the factor of safety is of practical significance. A series of normal stress distributions are represented by a cubic spline function with five discrete points，and the associated factors of safety are computed according to the force and moment equilibrium conditions for the whole sliding body. Comparisons are made between the differences in values of factors of safety and the reasonableness of the internal forces is checked. Example studies show that the maximum differences in values of factors of safety with different normal stress distributions are within 19%，which is reduced to be less than 7% after checking the internal forces.
