Abstract: In this paper, a generalized equation of three dimensional limit equilibrium methods for slope stability analysis is developed under the four assumptions. They are: (1) The safety factor is defined as the strength reduction factor of materials; (2) The soil is looked as rigid body, and the sliding surface obeys the Mohr-Columb strength broken criterion; (3) The action position of dNz locates at the middle of the bottom of a column; (4) The angle q is the angle between the shearing force of the sliding surface and the intersection of the sliding surface and the xoz plane. This equation can give the equations associated with the general three dimensional limit equilibrium, the simplified Bishop three dimensional limit equilibrium, the simplified Janbu three dimensional limit equilibrium, or the Spencer three dimensional limit equilibrium on the basis of the confined conditions for each specific method.