In the slope stability analysis, limit equilibrium method is based on the safety factor as the judgment standard,and nowadays the method to determine the safety coefficient need complex iterative calculation which can’t quickly to determine the safety coefficient in the different current situation of engineering. Based on the Spencer method of limit equilibrium and shear strength reduction finite element method (SSR-FEM), establishing a method which can make up for the disadvantages of computational complexity and judgment phrase to determine the slope stability safety coefficient rapidly and preliminarily. Firstly, considering main factors such as the natural conditions, groundwater conditions and earthquake intensity,the study use a slice coding method in the computer Spencer’s slope stability analysis program,building the charts of the nonlinear failure envelops and the nonlinear failure envelops are analyzed in detail.Secondly,based on the test datas,analysis the influence of earthquake intensity, coeffient of pore water pressure and etc.to the safety factor.The results show that the the stability charts which established by the nonlinear failure envelopes can rapidly and accurately establish the safety factor of the slope.